6 files declare their use of ConfigEntityBundleBase in Zircon Profile 8

BlockContentType.php in core/modules/block_content/src/Entity/BlockContentType.php

Contains \Drupal\block_content\Entity\BlockContentType.

CommentType.php in core/modules/comment/src/Entity/CommentType.php

Contains \Drupal\comment\Entity\CommentType.

ContactForm.php in core/modules/contact/src/Entity/ContactForm.php

Contains \Drupal\contact\Entity\ContactForm.

NodeType.php in core/modules/node/src/Entity/NodeType.php

Contains \Drupal\node\Entity\NodeType.

ShortcutSet.php in core/modules/shortcut/src/Entity/ShortcutSet.php

Contains \Drupal\shortcut\Entity\ShortcutSet.

Vocabulary.php in core/modules/taxonomy/src/Entity/Vocabulary.php

Contains \Drupal\taxonomy\Entity\Vocabulary.