For some albums that have no Cover Art Picard will download a random cover art that is consistent across multiple releases. (I've noticed the same art shows up in Plex, so perhaps this is an issue with some other component?)

For instance, all of these have same wrong cover art in Picard (Attached).

Release “Get On Up! Joe Gibbs Rocksteady, 1967–1968” by Various Artists - Cover Art - MusicBrainz 

Release “More Kidz Bop Gold” by Kidz Bop - MusicBrainz

Release “The Art Of Saying Nothing” by Imperial Leisure - MusicBrainz

Release “Bitter River” by Pygmy Lush - MusicBrainz