The cover art gallery viewer seems to be activated twice on some pages. At first I noticed that it was apparently not possible to close it with the Escape key as usual and that the overlay opacity was higher.

The fact that the dialog was opened twice wasn't obvious at first as most uploads were square front covers and were at the exact same position. On rectangular (or when navigating to next/previous) images it became clear what was happening:

confirmed so far:
edit/subscribed
edit/subscribed_editors
user/<name>/edits
user/<name>/edits/open