I found two releases that still have old web archive cover art links, but it's afaict impossible to remove the links. All I could find was "The artwork in the sidebar is being provided by a [URL relationship] (<- this link is broken/incomplete)." in the CAA tab.
https://musicbrainz.org/release/3b3c76fe-2b5b-35b5-b84f-5bdadcd44af9
https://musicbrainz.org/release/0cf29b4c-e9be-43fe-be23-250a0a9e592f

I then tried to find the reports about deprecated CA links but they were apparently removed last year and there is no longer any info available on what you were supposed to do when you come across this. Maybe just add cover art to CAA which then "hides" the deprecated relationship? Removing the feature completely from the MB code might be a better idea?