Revision object is returned instead of revision id due to core type upcasting change.

@sahilgidwani Thank you for submitting the patch in your comment #2. I have reviewed it and found that it worked correctly.

Since node_revision_load is deprecated in Drupal 10.1.0 and will be removed in Drupal 11.0.0, I have submitted a new patch that uses \Drupal\Core\Entity\RevisionableStorageInterface::loadRevision instead.

Thank you both, this issue is indeed major as it is a WSOD for content editors. I have reviewed the patches and tested it out and it works well.