If possible the process for getting the cover art from Spotify needs an update so it grabs the highest resolution.
I have recently learned that Spotify does have higher than 640x640 resolutions but a-tisket (also Harmony and the MB: Enhanced Cover Art Uploads script) doesn’t grab anything higher. I am not sure where the differences lie but sites like https://covers.musichoarders.xyz/ can find the higher Spotify resolutions, so I imagine it should be possible for a-tisket to do as well.