Picard sometimes can't find the cover (in my case) "Front." However, such a cover exists in the database. After checking the debug in Picard, it turns out that such cases have the type "unknown," but not "Other." In short, when the word "unknown" appears, Picard rejects the request.

Here's the link to the thread:

https://community.metabrainz.org/t/picard-refuses-to-take-off-this-cover-despite-numerous-attempts/814881