I came here with the same question. The entry on my Extend page shows
Machine name: footnotes
Version: 3.1.0
Requires: FakeObjects (disabled), CKEditor 4 (contrib) (disabled), Text Editor, Filter, User, System, FileField
Drupal 10.1.5
I see in the info.yml and the install file that Footnotes only has
dependencies:
- 'fakeobjects:fakeobjects'
Going to that module shows it has a dependency on CKEditor, as is where the v4 issue is coming from. Therefore, I believe this issue either requires a rewrite of that handling to remove the dependency, or just point this issue to the one at the FakeObjects 📌 Plan what's needed for ckeditor 5 in Drupal 9.3+ / Drupal 10 Active module and close it.