diff --git a/core/lib/Drupal/Core/Extension/Extension.php b/core/lib/Drupal/Core/Extension/Extension.php
index 0b3fc6c57976..17ca3fe7dc3d 100644
--- a/core/lib/Drupal/Core/Extension/Extension.php
+++ b/core/lib/Drupal/Core/Extension/Extension.php
@@ -192,4 +192,21 @@ class Extension {
     $this->root = $container && $container->hasParameter('app.root') ? $container->getParameter('app.root') : DRUPAL_ROOT;
   }
 
+  /**
+   * Checks if an extension is marked as experimental.
+   *
+   * @return bool
+   *   TRUE if an extension is marked as experimental, FALSE otherwise.
+   */
+  public function isExperimental(): bool {
+    // Currently, this function checks for both the key/value pairs
+    // 'experimental: true' and 'lifecycle: experimental' to determine if an
+    // extension is marked as experimental.
+    // @todo Remove the check for 'experimental: true' as part of
+    // https://www.drupal.org/node/3250342
+    return (isset($this->info['experimental']) && $this->info['experimental'])
+    || (isset($this->info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER])
+        && $this->info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::EXPERIMENTAL);
+  }
+
 }
diff --git a/core/modules/system/src/Controller/SystemController.php b/core/modules/system/src/Controller/SystemController.php
index 41e351faf81b..83b2bcce5794 100644
--- a/core/modules/system/src/Controller/SystemController.php
+++ b/core/modules/system/src/Controller/SystemController.php
@@ -225,7 +225,6 @@ class SystemController extends ControllerBase {
       }
       $theme->is_default = ($theme->getName() == $theme_default);
       $theme->is_admin = ($theme->getName() == $admin_theme || ($theme->is_default && empty($admin_theme)));
-      $theme->is_experimental = isset($theme->info['experimental']) && $theme->info['experimental'];
 
       // Identify theme screenshot.
       $theme->screenshot = NULL;
@@ -330,7 +329,7 @@ class SystemController extends ControllerBase {
               'attributes' => ['title' => $this->t('Set @theme as default theme', ['@theme' => $theme->info['name']])],
             ];
           }
-          $admin_theme_options[$theme->getName()] = $theme->info['name'] . ($theme->is_experimental ? ' (' . t('Experimental') . ')' : '');
+          $admin_theme_options[$theme->getName()] = $theme->info['name'] . ($theme->isExperimental() ? ' (' . t('Experimental') . ')' : '');
         }
         else {
           $theme->operations[] = [
@@ -357,7 +356,7 @@ class SystemController extends ControllerBase {
       if ($theme->is_admin) {
         $theme->notes[] = $this->t('administration theme');
       }
-      if ($theme->is_experimental) {
+      if ($theme->isExperimental()) {
         $theme->notes[] = $this->t('experimental theme');
       }
 
diff --git a/core/modules/system/src/Controller/ThemeController.php b/core/modules/system/src/Controller/ThemeController.php
index 1f3e61865cb8..21fae3ccc5a3 100644
--- a/core/modules/system/src/Controller/ThemeController.php
+++ b/core/modules/system/src/Controller/ThemeController.php
@@ -187,7 +187,7 @@ class ThemeController extends ControllerBase {
     $themes_to_enable = array_merge([$theme], $dependencies);
 
     foreach ($themes_to_enable as $name) {
-      if (!empty($all_themes[$name]->info['experimental']) && $all_themes[$name]->status === 0) {
+      if (isset($all_themes[$name]) && $all_themes[$name]->isExperimental() && $all_themes[$name]->status === 0) {
         return TRUE;
       }
     }
diff --git a/core/modules/system/src/Form/ThemeExperimentalConfirmForm.php b/core/modules/system/src/Form/ThemeExperimentalConfirmForm.php
index c9c993775161..9982ac762377 100644
--- a/core/modules/system/src/Form/ThemeExperimentalConfirmForm.php
+++ b/core/modules/system/src/Form/ThemeExperimentalConfirmForm.php
@@ -104,7 +104,7 @@ class ThemeExperimentalConfirmForm extends ConfirmFormBase {
     $dependencies = array_keys($all_themes[$theme]->requires);
     $themes = array_merge([$theme], $dependencies);
     $is_experimental = function ($theme) use ($all_themes) {
-      return isset($all_themes[$theme]) && isset($all_themes[$theme]->info['experimental']) && $all_themes[$theme]->info['experimental'];
+      return isset($all_themes[$theme]) && $all_themes[$theme]->isExperimental();
     };
     $get_label = function ($theme) use ($all_themes) {
       return $all_themes[$theme]->info['name'];
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index b24d7d1651ae..28335c75d08f 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -33,8 +33,12 @@ use Symfony\Component\HttpFoundation\Request;
 function system_requirements($phase) {
   global $install_state;
   // Reset the extension lists.
-  \Drupal::service('extension.list.module')->reset();
-  \Drupal::service('extension.list.theme')->reset();
+  /** @var \Drupal\Core\Extension\ModuleExtensionList $module_extension_list */
+  $module_extension_list = \Drupal::service('extension.list.module');
+  $module_extension_list->reset();
+  /** @var \Drupal\Core\Extension\ThemeExtensionList $theme_extension_list */
+  $theme_extension_list = \Drupal::service('extension.list.theme');
+  $theme_extension_list->reset();
   $requirements = [];
 
   // Report Drupal version
@@ -50,7 +54,7 @@ function system_requirements($phase) {
     // is not running the default installation profile.
     $profile = \Drupal::installProfile();
     if ($profile != 'standard') {
-      $info = \Drupal::service('extension.list.module')->getExtensionInfo($profile);
+      $info = $module_extension_list->getExtensionInfo($profile);
       $requirements['install_profile'] = [
         'title' => t('Installation profile'),
         'value' => t('%profile_name (%profile-%version)', [
@@ -63,15 +67,27 @@ function system_requirements($phase) {
       ];
     }
 
-    // Warn if any experimental modules are installed.
+    // Gather all obsolete and experimental modules being enabled.
+    $obsolete_extensions = [];
+    $deprecated_modules = [];
     $experimental_modules = [];
     $enabled_modules = \Drupal::moduleHandler()->getModuleList();
     foreach ($enabled_modules as $module => $data) {
-      $info = \Drupal::service('extension.list.module')->getExtensionInfo($module);
-      if (isset($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER]) && $info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::EXPERIMENTAL) {
-        $experimental_modules[$module] = $info['name'];
+      $info = $module_extension_list->getExtensionInfo($module);
+      if (isset($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER])) {
+        if ($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::EXPERIMENTAL) {
+          $experimental_modules[$module] = $info['name'];
+        }
+        elseif ($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::DEPRECATED) {
+          $deprecated_modules[] = ['name' => $info['name'], 'lifecycle_link' => $info['lifecycle_link']];
+        }
+        elseif ($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::OBSOLETE) {
+          $obsolete_extensions[$module] = ['name' => $info['name'], 'lifecycle_link' => $info['lifecycle_link']];
+        }
       }
     }
+
+    // Warn if any experimental modules are installed.
     if (!empty($experimental_modules)) {
       $requirements['experimental_modules'] = [
         'title' => t('Experimental modules enabled'),
@@ -79,14 +95,48 @@ function system_requirements($phase) {
         'severity' => REQUIREMENT_WARNING,
       ];
     }
-    // Warn if any experimental themes are installed.
+    // Warn if any deprecated modules are installed.
+    if (!empty($deprecated_modules)) {
+      foreach ($deprecated_modules as $deprecated_module) {
+        $deprecated_modules_link_list[] = (string) Link::fromTextAndUrl($deprecated_module['name'], Url::fromUri($deprecated_module['lifecycle_link']))->toString();
+      }
+      $requirements['deprecated_modules'] = [
+        'title' => t('Deprecated modules enabled'),
+        'value' => t('Deprecated modules found: %module_list.', [
+          '%module_list' => t(implode(',', $deprecated_modules_link_list)),
+        ]),
+        'severity' => REQUIREMENT_WARNING,
+      ];
+    }
+
+    // Gather all obsolete and experimental themes being enabled.
     $experimental_themes = [];
+    $deprecated_themes = [];
     $installed_themes = \Drupal::service('theme_handler')->listInfo();
     foreach ($installed_themes as $theme => $data) {
+      $info = $theme_extension_list->getExtensionInfo($theme);
+      if (isset($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER])) {
+        if ($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::EXPERIMENTAL) {
+          $experimental_themes[$theme] = $info['name'];
+        }
+        elseif ($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::DEPRECATED) {
+          $deprecated_themes[] = ['name' => $info['name'], 'lifecycle_link' => $info['lifecycle_link']];
+        }
+        elseif ($info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::OBSOLETE) {
+          $obsolete_extensions[$theme] = ['name' => $info['name'], 'lifecycle_link' => $info['lifecycle_link']];
+        }
+      }
+      // Currently, we check for both the key/value pairs 'experimental: true'
+      // and 'lifecycle: experimental' to determine if an extension is marked as
+      // experimental.
+      // @todo Remove the check for 'experimental: true' as part of
+      // https://www.drupal.org/node/3250342
       if (isset($data->info['experimental']) && $data->info['experimental']) {
         $experimental_themes[$theme] = $data->info['name'];
       }
     }
+
+    // Warn if any experimental themes are enabled.
     if (!empty($experimental_themes)) {
       $requirements['experimental_themes'] = [
         'title' => t('Experimental themes enabled'),
@@ -94,6 +144,35 @@ function system_requirements($phase) {
         'severity' => REQUIREMENT_WARNING,
       ];
     }
+
+    // Warn if any deprecated themes are enabled.
+    if (!empty($deprecated_themes)) {
+      foreach ($deprecated_themes as $deprecated_theme) {
+        $deprecated_themes_link_list[] = (string) Link::fromTextAndUrl($deprecated_theme['name'], Url::fromUri($deprecated_theme['lifecycle_link']))->toString();
+
+      }
+      $requirements['deprecated_themes'] = [
+        'title' => t('Deprecated themes enabled'),
+        'value' => t('Deprecated themes found: %theme_list.', [
+          '%theme_list' => t(implode(',', $deprecated_themes_link_list)),
+        ]),
+        'severity' => REQUIREMENT_WARNING,
+      ];
+    }
+
+    // Warn if any obsolete extensions (themes or modules) are enabled.
+    if (!empty($obsolete_extensions)) {
+      foreach ($obsolete_extensions as $obsolete_extension) {
+        $obsolete_extensions_link_list[] = (string) Link::fromTextAndUrl($obsolete_extension['name'], Url::fromUri($obsolete_extension['lifecycle_link']))->toString();
+      }
+      $requirements['obsolete_extensions'] = [
+        'title' => t('Obsolete extensions enabled'),
+        'value' => t('Obsolete extensions found: %extensions. Obsolete extensions are provided only so that they can be uninstalled cleanly. You should immediately uninstall these extensions since they may be removed in a future release.', [
+          '%extension_list' => t(implode(', ', $obsolete_extensions_link_list)),
+        ]),
+        'severity' => REQUIREMENT_WARNING,
+      ];
+    }
     _system_advisories_requirements($requirements);
   }
 
@@ -931,8 +1010,8 @@ function system_requirements($phase) {
       ];
     };
     $profile = \Drupal::installProfile();
-    $files = \Drupal::service('extension.list.module')->getList();
-    $files += \Drupal::service('extension.list.theme')->getList();
+    $files = $module_extension_list->getList();
+    $files += $theme_extension_list->getList();
     $core_incompatible_extensions = [];
     $php_incompatible_extensions = [];
     foreach ($files as $extension_name => $file) {
@@ -1048,10 +1127,8 @@ function system_requirements($phase) {
 
     // Look for invalid modules.
     $extension_config = \Drupal::configFactory()->get('core.extension');
-    /** @var \Drupal\Core\Extension\ExtensionList $extension_list */
-    $extension_list = \Drupal::service('extension.list.module');
-    $is_missing_extension = function ($extension_name) use (&$extension_list) {
-      return !$extension_list->exists($extension_name);
+    $is_missing_extension = function ($extension_name) use (&$module_extension_list) {
+      return !$module_extension_list->exists($extension_name);
     };
 
     $invalid_modules = array_filter(array_keys($extension_config->get('module')), $is_missing_extension);
@@ -1073,8 +1150,10 @@ function system_requirements($phase) {
     }
 
     // Look for invalid themes.
-    $extension_list = \Drupal::service('extension.list.theme');
-    $invalid_themes = array_filter(array_keys($extension_config->get('theme')), $is_missing_extension);
+    $is_missing_theme = function ($extension_name) use (&$theme_extension_list) {
+      return !$theme_extension_list->exists($extension_name);
+    };
+    $invalid_themes = array_filter(array_keys($extension_config->get('theme')), $is_missing_theme);
     if (!empty($invalid_themes)) {
       $requirements['invalid_theme'] = $create_extension_incompatibility_list(
         $invalid_themes,
@@ -1283,7 +1362,7 @@ function system_requirements($phase) {
       if ($last_removed && $last_removed > $update_registry->getInstalledVersion($module)) {
 
         /** @var \Drupal\Core\Extension\Extension $module_info */
-        $module_info = \Drupal::service('extension.list.module')->get($module);
+        $module_info = $module_extension_list->get($module);
         $module_list[$module] = [
           'name' => $module_info->info['name'],
           'last_removed' => $last_removed,
@@ -1327,7 +1406,6 @@ function system_requirements($phase) {
       $existing_updates = \Drupal::service('keyvalue')->get('post_update')->get('existing_updates', []);
       $post_update_registry = \Drupal::service('update.post_update_registry');
       $modules = \Drupal::moduleHandler()->getModuleList();
-      $module_extension_list = \Drupal::service('extension.list.module');
       foreach ($modules as $module => $extension) {
         $module_info = $module_extension_list->get($module);
         $removed_post_updates = $post_update_registry->getRemovedPostUpdates($module);
diff --git a/core/modules/system/tests/src/Functional/System/StatusTest.php b/core/modules/system/tests/src/Functional/System/StatusTest.php
index f2d9fb479eb2..3eb7ee334dca 100644
--- a/core/modules/system/tests/src/Functional/System/StatusTest.php
+++ b/core/modules/system/tests/src/Functional/System/StatusTest.php
@@ -99,6 +99,45 @@ class StatusTest extends BrowserTestBase {
     ]);
     $this->assertCount(1, $elements);
     $this->assertStringStartsWith('Available', $elements[0]->getParent()->getText());
+
+    // Test the page with deprecated extensions.
+    $module_installer = \Drupal::service('module_installer');
+    $session = $this->assertSession();
+
+    // Install a deprecated module.
+    $module_installer->install(['deprecated_module']);
+    $this->drupalGet('admin/reports/status');
+
+    // Confirm warning messages are displayed for the deprecated module.
+    $session->pageTextContains('Deprecated modules enabled');
+    $session->pageTextContains('Deprecated modules found: Deprecated module.');
+
+    // Check that the deprecated module link was rendered correctly.
+    $this->assertSession()->elementExists('xpath', "//a[contains(@href, 'http://example.com/deprecated')]");
+
+    // Uninstall a deprecated module and confirm the warning is not displayed.
+    $module_installer->uninstall(['deprecated_module']);
+    $this->drupalGet('admin/reports/status');
+    $session->pageTextNotContains('Deprecated modules enabled');
+    $session->pageTextNotContains('Deprecated modules found: Deprecated module.');
+    $this->assertSession()->elementNotExists('xpath', "//a[contains(@href, 'http://example.com/deprecated')]");
+
+    // Install deprecated theme and confirm warning message is displayed.
+    $theme_installer = \Drupal::service('theme_installer');
+    $theme_installer->install(['test_deprecated_theme']);
+    $this->drupalGet('admin/reports/status');
+    $session->pageTextContains('Deprecated themes enabled');
+    $session->pageTextContains('Deprecated themes found: Test deprecated theme.');
+
+    // Check that the deprecated theme link was rendered correctly.
+    $this->assertSession()->elementExists('xpath', "//a[contains(@href, 'http://example.com/deprecated_theme')]");
+
+    // Uninstall a deprecated theme and confirm the warning is not displayed.
+    $theme_installer->uninstall(['test_deprecated_theme']);
+    $this->drupalGet('admin/reports/status');
+    $session->pageTextNotContains('Deprecated themes enabled');
+    $session->pageTextNotContains('Deprecated themes found: Test deprecated theme.');
+    $this->assertSession()->elementNotExists('xpath', "//a[contains(@href, 'http://example.com/deprecated_theme')]");
   }
 
 }
diff --git a/core/modules/system/tests/src/Functional/Theme/ExperimentalThemeTest.php b/core/modules/system/tests/src/Functional/Theme/ExperimentalThemeTest.php
index 58a6e3933efb..d3cee2a02d07 100644
--- a/core/modules/system/tests/src/Functional/Theme/ExperimentalThemeTest.php
+++ b/core/modules/system/tests/src/Functional/Theme/ExperimentalThemeTest.php
@@ -5,7 +5,7 @@ namespace Drupal\Tests\system\Functional\Theme;
 use Drupal\Tests\BrowserTestBase;
 
 /**
- * Tests the installation of themes.
+ * Tests the installation of experimental themes.
  *
  * @group Theme
  */
@@ -37,16 +37,17 @@ class ExperimentalThemeTest extends BrowserTestBase {
 
   /**
    * Tests installing experimental themes and dependencies in the UI.
+   *
+   * @dataProvider providerTestExperimentalConfirmForm
    */
-  public function testExperimentalConfirmForm() {
+  public function testExperimentalConfirmForm(string $theme_name, string $dependency_theme_name, string $machine_theme_name, string $machine_dependency_theme_name): void {
     // Only experimental themes should be marked as such with a parenthetical.
     $this->drupalGet('admin/appearance');
-    $this->assertSession()->responseContains(sprintf('Experimental test %s                (experimental theme)', \Drupal::VERSION));
-    $this->assertSession()->responseContains(sprintf('Experimental dependency test %s', \Drupal::VERSION));
+    $this->assertSession()->responseContains(sprintf($theme_name . ' %s                (experimental theme)', \Drupal::VERSION));
+    $this->assertSession()->responseContains(sprintf($dependency_theme_name . ' %s', \Drupal::VERSION));
 
     // First, test installing a non-experimental theme with no dependencies.
     // There should be no confirmation form and no experimental theme warning.
-    $this->drupalGet('admin/appearance');
     $this->cssSelect('a[title="Install <strong>Test theme</strong> theme"]')[0]->click();
     $this->assertSession()->pageTextContains('The <strong>Test theme</strong> theme has been installed.');
     $this->assertSession()->pageTextNotContains('Experimental modules are provided for testing purposes only.');
@@ -55,12 +56,12 @@ class ExperimentalThemeTest extends BrowserTestBase {
     // There should be a confirmation form with an experimental warning, but no
     // list of dependencies.
     $this->drupalGet('admin/appearance');
-    $this->cssSelect('a[title="Install Experimental test theme"]')[0]->click();
+    $this->cssSelect('a[title="Install ' . $theme_name . ' theme"]')[0]->click();
     $this->assertSession()->pageTextContains('Experimental themes are provided for testing purposes only. Use at your own risk.');
 
     // The module should not be enabled and there should be a warning and a
     // list of the experimental modules with only this one.
-    $this->assertSession()->pageTextNotContains('The Experimental Test theme has been installed.');
+    $this->assertSession()->pageTextNotContains('The ' . $theme_name . ' theme has been installed.');
     $this->assertSession()->pageTextContains('Experimental themes are provided for testing purposes only.');
 
     // There should be no message about enabling dependencies.
@@ -68,69 +69,104 @@ class ExperimentalThemeTest extends BrowserTestBase {
 
     // Enable the theme and confirm that it worked.
     $this->submitForm([], 'Continue');
-    $this->assertSession()->pageTextContains('The Experimental test theme has been installed.');
+    $this->assertSession()->pageTextContains('The ' . $theme_name . ' theme has been installed.');
 
     // Setting it as the default should not ask for another confirmation.
-    $this->cssSelect('a[title="Set Experimental test as default theme"]')[0]->click();
+    $this->cssSelect('a[title="Set ' . $theme_name . ' as default theme"]')[0]->click();
     $this->assertSession()->pageTextNotContains('Experimental themes are provided for testing purposes only. Use at your own risk.');
-    $this->assertSession()->pageTextContains('Experimental test is now the default theme.');
-    $this->assertSession()->pageTextNotContains(sprintf('Experimental test %s                (experimental theme)', \Drupal::VERSION));
-    $this->assertSession()->responseContains(sprintf('Experimental test %s                (default theme, administration theme, experimental theme)', \Drupal::VERSION));
+    $this->assertSession()->pageTextContains($theme_name . ' is now the default theme.');
+    $this->assertSession()->pageTextNotContains(sprintf($theme_name . ' %s                (experimental theme)', \Drupal::VERSION));
+    $this->assertSession()->responseContains(sprintf($theme_name . ' %s                (default theme, administration theme, experimental theme)', \Drupal::VERSION));
 
     // Uninstall the theme.
     $this->config('system.theme')->set('default', 'test_theme')->save();
     \Drupal::service('theme_handler')->refreshInfo();
-    \Drupal::service('theme_installer')->uninstall(['experimental_theme_test']);
+    \Drupal::service('theme_installer')->uninstall([$machine_theme_name]);
 
     // Reinstall the same experimental theme, but this time immediately set it
     // as the default. This should again trigger a confirmation form with an
     // experimental warning.
     $this->drupalGet('admin/appearance');
-    $this->cssSelect('a[title="Install Experimental test as default theme"]')[0]->click();
+    $this->cssSelect('a[title="Install ' . $theme_name . ' as default theme"]')[0]->click();
     $this->assertSession()->pageTextContains('Experimental themes are provided for testing purposes only. Use at your own risk.');
 
     // Test enabling a theme that is not itself experimental, but that depends
     // on an experimental module.
     $this->drupalGet('admin/appearance');
-    $this->cssSelect('a[title="Install Experimental dependency test theme"]')[0]->click();
+    $this->cssSelect('a[title="Install ' . $dependency_theme_name . ' theme"]')[0]->click();
 
     // The theme should not be enabled and there should be a warning and a
     // list of the experimental modules with only this one.
-    $this->assertSession()->pageTextNotContains('The Experimental dependency test theme has been installed.');
+    $this->assertSession()->pageTextNotContains('The ' . $dependency_theme_name . ' theme has been installed.');
     $this->assertSession()->pageTextContains('Experimental themes are provided for testing purposes only. Use at your own risk.');
-    $this->assertSession()->pageTextContains('The following themes are experimental: Experimental test');
+    $this->assertSession()->pageTextContains('The following themes are experimental: ' . $theme_name);
 
     // Ensure the non-experimental theme is not listed as experimental.
-    $this->assertSession()->pageTextNotContains('The following themes are experimental: Experimental test, Experimental dependency test');
-    $this->assertSession()->pageTextNotContains('The following themes are experimental: Experimental dependency test');
+    $this->assertSession()->pageTextNotContains('The following themes are experimental: ' . $theme_name . ', ' . $dependency_theme_name);
+    $this->assertSession()->pageTextNotContains('The following themes are experimental: ' . $dependency_theme_name);
 
     // There should be a message about enabling dependencies.
-    $this->assertSession()->pageTextContains('You must enable the Experimental test theme to install Experimental dependency test');
+    $this->assertSession()->pageTextContains('You must enable the ' . $theme_name . ' theme to install ' . $dependency_theme_name);
 
     // Enable the theme and confirm that it worked.
     $this->submitForm([], 'Continue');
-    $this->assertSession()->pageTextContains('The Experimental dependency test theme has been installed.');
-    $this->assertSession()->responseContains(sprintf('Experimental test %s                (experimental theme)', \Drupal::VERSION));
-    $this->assertSession()->responseContains(sprintf('Experimental dependency test %s', \Drupal::VERSION));
+    $this->assertSession()->pageTextContains('The ' . $dependency_theme_name . ' theme has been installed.');
+    $this->assertSession()->responseContains(sprintf($theme_name . ' %s                (experimental theme)', \Drupal::VERSION));
+    $this->assertSession()->responseContains(sprintf($dependency_theme_name . ' %s', \Drupal::VERSION));
 
     // Setting it as the default should not ask for another confirmation.
-    $this->cssSelect('a[title="Set Experimental dependency test as default theme"]')[0]->click();
+    $this->cssSelect('a[title="Set ' . $dependency_theme_name . ' as default theme"]')[0]->click();
     $this->assertSession()->pageTextNotContains('Experimental themes are provided for testing purposes only. Use at your own risk.');
-    $this->assertSession()->pageTextContains('Experimental dependency test is now the default theme.');
-    $this->assertSession()->responseContains(sprintf('Experimental test %s                (experimental theme)', \Drupal::VERSION));
-    $this->assertSession()->responseContains(sprintf('Experimental dependency test %s                (default theme, administration theme)', \Drupal::VERSION));
+    $this->assertSession()->pageTextContains($dependency_theme_name . ' is now the default theme.');
+    $this->assertSession()->responseContains(sprintf($theme_name . ' %s                (experimental theme)', \Drupal::VERSION));
+    $this->assertSession()->responseContains(sprintf($dependency_theme_name . ' %s                (default theme, administration theme)', \Drupal::VERSION));
 
     // Uninstall the theme.
     $this->config('system.theme')->set('default', 'test_theme')->save();
     \Drupal::service('theme_handler')->refreshInfo();
-    \Drupal::service('theme_installer')->uninstall(['experimental_theme_test', 'experimental_theme_dependency_test']);
+    \Drupal::service('theme_installer')->uninstall(
+      [$machine_theme_name, $machine_dependency_theme_name]
+    );
 
     // Reinstall the same theme, but this time immediately set it as the
     // default. This should again trigger a confirmation form with an
     // experimental warning for its dependency.
     $this->drupalGet('admin/appearance');
-    $this->cssSelect('a[title="Install Experimental dependency test as default theme"]')[0]->click();
+    $this->cssSelect('a[title="Install ' . $dependency_theme_name . ' as default theme"]')[0]->click();
     $this->assertSession()->pageTextContains('Experimental themes are provided for testing purposes only. Use at your own risk.');
   }
 
+  /**
+   * Data provider for experimental test themes.
+   *
+   * @return string[][]
+   *   An array with four items:
+   *   - The theme name.
+   *   - The dependency theme name.
+   *   - The machine theme name.
+   *   - The machine dependency theme name.
+   *
+   * @todo Turn the check for 'Testing legacy Key/Value pair
+   * "experimental: true"' into a @legacy test triggering a deprecation as part
+   * of https://www.drupal.org/node/3250342
+   */
+  public function providerTestExperimentalConfirmForm(): array {
+    return [
+      'Testing Key/Value pair "lifecycle: experimental"' =>
+        [
+          'Experimental test',
+          'Experimental dependency test',
+          'experimental_theme_test',
+          'experimental_theme_dependency_test',
+        ],
+      'Testing legacy Key/Value pair "experimental: true"' =>
+        [
+          'Legacy experimental test',
+          'Legacy experimental dependency test',
+          'legacy_experimental_theme_test',
+          'legacy_experimental_theme_dependency_test',
+        ],
+    ];
+  }
+
 }
diff --git a/core/modules/system/tests/themes/experimental_theme_test/experimental_theme_test.info.yml b/core/modules/system/tests/themes/experimental_theme_test/experimental_theme_test.info.yml
index a2f4463902fc..587ceb13aa23 100644
--- a/core/modules/system/tests/themes/experimental_theme_test/experimental_theme_test.info.yml
+++ b/core/modules/system/tests/themes/experimental_theme_test/experimental_theme_test.info.yml
@@ -3,4 +3,4 @@ type: theme
 description: 'Experimental test theme.'
 version: VERSION
 base theme: false
-experimental: true
+lifecycle: experimental
diff --git a/core/modules/system/tests/themes/legacy_experimental_theme_dependency_test/legacy_experimental_theme_dependency_test.info.yml b/core/modules/system/tests/themes/legacy_experimental_theme_dependency_test/legacy_experimental_theme_dependency_test.info.yml
new file mode 100644
index 000000000000..dc6173c130af
--- /dev/null
+++ b/core/modules/system/tests/themes/legacy_experimental_theme_dependency_test/legacy_experimental_theme_dependency_test.info.yml
@@ -0,0 +1,5 @@
+name: 'Legacy experimental dependency test'
+type: theme
+description: 'Legacy experimental dependency test theme.'
+version: VERSION
+base theme: legacy_experimental_theme_test
diff --git a/core/modules/system/tests/themes/legacy_experimental_theme_test/legacy_experimental_theme_test.info.yml b/core/modules/system/tests/themes/legacy_experimental_theme_test/legacy_experimental_theme_test.info.yml
new file mode 100644
index 000000000000..448d85442498
--- /dev/null
+++ b/core/modules/system/tests/themes/legacy_experimental_theme_test/legacy_experimental_theme_test.info.yml
@@ -0,0 +1,6 @@
+name: 'Legacy experimental test'
+type: theme
+description: 'Legacy experimental test theme.'
+version: VERSION
+base theme: false
+experimental: true
diff --git a/core/modules/system/tests/themes/test_deprecated_theme/test_deprecated_theme.info.yml b/core/modules/system/tests/themes/test_deprecated_theme/test_deprecated_theme.info.yml
new file mode 100644
index 000000000000..92c3ad51ea78
--- /dev/null
+++ b/core/modules/system/tests/themes/test_deprecated_theme/test_deprecated_theme.info.yml
@@ -0,0 +1,7 @@
+name: 'Test deprecated theme'
+type: theme
+description: 'Support module for testing deprecated themes.'
+version: VERSION
+base theme: false
+lifecycle: deprecated
+lifecycle_link: 'http://example.com/deprecated_theme'
diff --git a/core/themes/claro/claro.info.yml b/core/themes/claro/claro.info.yml
index 07be922f74d4..94c8f9b9c2f8 100644
--- a/core/themes/claro/claro.info.yml
+++ b/core/themes/claro/claro.info.yml
@@ -17,7 +17,7 @@ description: 'A clean, accessible, and powerful Drupal administration theme.'
 alt text: 'Screenshot of Claro, Drupal administration theme.'
 package: Core
 version: VERSION
-experimental: true
+lifecycle: experimental
 libraries:
   - core/drupal.message
   - core/normalize