I chose 2.11, but this has been an issue ever since I started using Picard, I just never bothered to ask or report.

Basically, as the title says, if you open a track/album with already embedded cover art and one of the cover art providers finds a different cover art, then it shows this new one and the tracks are in "Excellent match" state, i.e. indicating it would change something on save. So far so good. When I choose the "Keep original cover art" option however (and there are no other changes to the tags), it doesn't return the track status to the green checkmark, i.e. "track saved"/"no changes".

This is in contrast to the opposite case: If the cover art remains unchanged and there are changes to the tags, one can choose to use the Original Value(s) and the tracks will return to the green checkmark.

Background: i have tracks where the fanart.tv plugin consistently finds the "wrong" cover art because it returns an image for a "basic" release while I have cover images for a Limited Edition embedded (since the plugin only chooses the first cover returned by the API, not providing a selection).
When one (or more) of the tracks have actual metadata changes (e.g. a Writer was added on Musicbrainz), keeping the original art should only show the remaining tracks with changes as having changes.