I'm slowly importing 25 years of last.fm data via CSV, and I've noticed that items are showing up with no, or incorrect, album art seemingly at random. Sometimes an album will show up intact, but then a day later the same album will have album art all over the place. I would understand this if my tags were bad, but the CSV records look fine, with album information and all.
What I see in the CSV file: https://raeokay.com/assets/img/csvdata.png
What I see in my Rocksky scrobbles on that date: https://raeokay.com/assets/img/rockskyalbums.png
I'm also getting a lot of, e.g., "(2016 Remaster)" entries for scrobbles where I certainly wasn't using Spotify, because it didn't exist yet, and neither did the remaster being mentioned (a 2016 remaster in the year 2008!). I've never included remaster info in my tag names. Obviously relying on Spotify as the primary metadata source explains that, but I wonder whether it somehow explains the other issue as well.
Yeah, this is a known issue with the current Spotify-based metadata matcher. It sometimes picks the wrong release of a track, which can result in incorrect album art or remaster versions being attached to older scrobbles.
I need to improve the matcher so it gives more weight to the album information from the CSV and picks the correct album/release instead of just the closest Spotify match.