Hmm, according to another user it still appears to work, so it doesn't seem like the issue has to do with an Instagram update (thankfully!). Did you by any chance log out of instagram? It only works when you're logged in.

If not, can you contact me through one of the contact links in the addon's description? Matrix or discord would be ideal as it might require a bit of back and forth to find out what the issue is (but if not email/github/reddit is fine too). The reason I ask is that unfortunately there's no way to have a discussion over the firefox addons review page, so I can't really help troubleshoot the issue here.

Sorry you're having this issue, and hope we can get this fixed! :)