From what I can tell, Iceshrimp.NET only fetches remote emojis the first time they're seen. So if someone updates the URL an emoji is at, emojis just break unless you go into the database manually and change the URL the emoji image is pulled from. Since IS.NET proxies all emojis, it might be a good idea to add checks to refetch emojis from the remote if they 404. Alternatively there could be a startup option to check all emoji and refetch if needed, like the media fixup and cleanup?

This just comes from me because a friend just re-imported like all of their emoji on their instance (Sharkey) and I don't wanna break existing reactions / posts by just dropping all of those emojis from the database. 😅