13 files declare their use of ConfigurableLanguageManagerInterface in Zircon Profile 8

AccountForm.php in core/modules/user/src/AccountForm.php

Contains \Drupal\user\AccountForm.

ConfigTranslationDeleteForm.php in core/modules/config_translation/src/Form/ConfigTranslationDeleteForm.php

Contains \Drupal\config_translation\Form\ConfigTranslationDeleteForm.

ConfigTranslationFormBase.php in core/modules/config_translation/src/Form/ConfigTranslationFormBase.php

Contains \Drupal\config_translation\Form\ConfigTranslationFormBase.

ConfigurableLanguage.php in core/modules/language/src/Entity/ConfigurableLanguage.php

Contains \Drupal\language\Entity\ConfigurableLanguage.

ImportForm.php in core/modules/locale/src/Form/ImportForm.php

Contains \Drupal\locale\Form\ImportForm.

LanguageBlock.php in core/modules/language/src/Plugin/Derivative/LanguageBlock.php

Contains \Drupal\language\Plugin\Derivative\LanguageBlock.

LanguageFormBase.php in core/modules/language/src/Form/LanguageFormBase.php

Contains \Drupal\language\Form\LanguageFormBase.

LanguageRequestSubscriber.php in core/modules/language/src/EventSubscriber/LanguageRequestSubscriber.php

Contains \Drupal\language\EventSubscriber\LanguageRequestSubscriber.

LocaleConfigManager.php in core/modules/locale/src/LocaleConfigManager.php

Contains \Drupal\locale\LocaleConfigManager.

LocaleDefaultConfigStorage.php in core/modules/locale/src/LocaleDefaultConfigStorage.php

Contains \Drupal\locale\LocaleDefaultConfigStorage.

NegotiationBrowserForm.php in core/modules/language/src/Form/NegotiationBrowserForm.php

Contains \Drupal\language\Form\NegotiationBrowserForm.

NegotiationConfigureForm.php in core/modules/language/src/Form/NegotiationConfigureForm.php

Contains \Drupal\language\Form\NegotiationConfigureForm.

PathProcessorLanguage.php in core/modules/language/src/HttpKernel/PathProcessorLanguage.php

Contains \Drupal\language\HttpKernel\PathProcessorLanguage.