diff --git a/core/modules/language/language.module b/core/modules/language/language.module
index 2bbbedb8083..1a0cf7f5458 100644
--- a/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -267,19 +267,6 @@ function language_get_default_langcode($entity_type, $bundle) {
   return $configuration->getDefaultLangcode();
 }
 
-/**
- * Reads language prefixes and uses the langcode if no prefix is set.
- *
- * @deprecated in drupal:8.0.0 and is removed from drupal:9.0.0. Use
- *   \Drupal::config('language.negotiation')->get('url.prefixes') instead.
- *
- * @see https://www.drupal.org/node/2912748
- */
-function language_negotiation_url_prefixes() {
-  @trigger_error("language_negotiation_url_prefixes() is deprecated in drupal:8.0.0 and is removed from drupal:9.0.0. Use \Drupal::config('language.negotiation')->get('url.prefixes') instead. See https://www.drupal.org/node/2912748", E_USER_DEPRECATED);
-  return \Drupal::config('language.negotiation')->get('url.prefixes');
-}
-
 /**
  * Update the list of prefixes from the installed languages.
  */
@@ -299,19 +286,6 @@ function language_negotiation_url_prefixes_update() {
   $config->set('url.prefixes', $prefixes)->save(TRUE);
 }
 
-/**
- * Reads language domains.
- *
- * @deprecated in drupal:8.0.0 and is removed from drupal:9.0.0. Use
- *   \Drupal::config('language.negotiation')->get('url.domains') instead.
- *
- * @see https://www.drupal.org/node/2912748
- */
-function language_negotiation_url_domains() {
-  @trigger_error("language_negotiation_url_domains() is deprecated in drupal:8.0.0 and is removed from drupal:9.0.0. Use \Drupal::config('language.negotiation')->get('url.domains') instead. See https://www.drupal.org/node/2912748", E_USER_DEPRECATED);
-  return \Drupal::config('language.negotiation')->get('url.domains');
-}
-
 /**
  * Implements hook_modules_installed().
  */
diff --git a/core/modules/language/src/Config/LanguageConfigFactoryOverride.php b/core/modules/language/src/Config/LanguageConfigFactoryOverride.php
index 11fcb925b3b..3c7010d0345 100644
--- a/core/modules/language/src/Config/LanguageConfigFactoryOverride.php
+++ b/core/modules/language/src/Config/LanguageConfigFactoryOverride.php
@@ -143,14 +143,6 @@ class LanguageConfigFactoryOverride extends ConfigFactoryOverrideBase implements
     return $this;
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function setLanguageFromDefault(LanguageDefault $language_default = NULL) {
-    $this->language = $language_default ? $language_default->get() : NULL;
-    return $this;
-  }
-
   /**
    * {@inheritdoc}
    */
diff --git a/core/modules/language/src/Config/LanguageConfigFactoryOverrideInterface.php b/core/modules/language/src/Config/LanguageConfigFactoryOverrideInterface.php
index 5a58bee9da9..dec0546b0f7 100644
--- a/core/modules/language/src/Config/LanguageConfigFactoryOverrideInterface.php
+++ b/core/modules/language/src/Config/LanguageConfigFactoryOverrideInterface.php
@@ -4,7 +4,6 @@ namespace Drupal\language\Config;
 
 use Drupal\Core\Config\ConfigFactoryOverrideInterface;
 use Drupal\Core\Language\LanguageInterface;
-use Drupal\Core\Language\LanguageDefault;
 
 /**
  * Defines the interface for a configuration factory language override object.
@@ -29,20 +28,6 @@ interface LanguageConfigFactoryOverrideInterface extends ConfigFactoryOverrideIn
    */
   public function setLanguage(LanguageInterface $language = NULL);
 
-  /**
-   * Sets the language to be used in configuration overrides from the default.
-   *
-   * @param \Drupal\Core\Language\LanguageDefault $language_default
-   *   The default language.
-   *
-   * @return $this
-   *
-   * @deprecated in drupal:8.3.0 and is removed from drupal:9.0.0. This
-   *   method has been replaced by injecting the default language into the
-   *   constructor.
-   */
-  public function setLanguageFromDefault(LanguageDefault $language_default = NULL);
-
   /**
    * Get language override for given language and configuration name.
    *