The 'default_language' key must be set to TRUE, tests will fail if it is randomly set to FALSE.
Additionally, some entities support bundles but do not require them for ::create() to be called.
For example, MenuLinkContent::preCreate() adds in a default bundle.
Finally, not all implementations of \Drupal\Core\Field\FieldItemInterface::generateSampleValue() return values, and they should not overwrite default values.
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.
Drupal 9.x give issue:
Drupal\Core\Entity\EntityStorageException: No entity bundle was specified in Drupal\Core\Entity\ContentEntityStorageBase->createWithSampleValues() (line 230 w .../public_html/web/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php).
If bundle isn't exist then get error. Bundle removed in Commerce when attribute removed from list but not from LayoutBuilder
Path not apply on branch 9.x (latest I test is 9.5.1)