14 files declare their use of SqlContentEntityStorage in Zircon Profile 8

CommentStorage.php in core/modules/comment/src/CommentStorage.php

Contains \Drupal\comment\CommentStorage.

ContentTranslationTestBase.php in core/modules/content_translation/src/Tests/ContentTranslationTestBase.php

Contains \Drupal\content_translation\Tests\ContentTranslationTestBase.

EntityTestNoLoadStorage.php in core/modules/system/tests/modules/entity_test/src/EntityTestNoLoadStorage.php

Contains \Drupal\entity_test\EntityTestNoLoadStorage.

FeedStorage.php in core/modules/aggregator/src/FeedStorage.php

Contains \Drupal\aggregator\FeedStorage.

FieldDataCountTest.php in core/modules/field/src/Tests/FieldDataCountTest.php

Contains \Drupal\field\Tests\FieldDataCountTest.

FileStorage.php in core/modules/file/src/FileStorage.php

Contains \Drupal\file\FileStorage.

ItemStorage.php in core/modules/aggregator/src/ItemStorage.php

Contains \Drupal\aggregator\ItemStorage.

NodeStorage.php in core/modules/node/src/NodeStorage.php

Contains \Drupal\node\NodeStorage.

SqlContentEntityStorageTest.php in core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageTest.php

Contains \Drupal\Tests\Core\Entity\Sql\SqlContentEntityStorageTest.

taxonomy.module in core/modules/taxonomy/taxonomy.module

Enables the organization of content into categories.

TermStorage.php in core/modules/taxonomy/src/TermStorage.php

Contains \Drupal\taxonomy\TermStorage.

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

Contains \Drupal\user\UserStorage.

views.views.inc in core/modules/views/views.views.inc

Provide views data that isn't tied to any other module.

ViewsEntitySchemaSubscriber.php in core/modules/views/src/EventSubscriber/ViewsEntitySchemaSubscriber.php

Contains \Drupal\views\EventSubscriber\ViewsEntitySchemaSubscriber.