For unknown reason, Mozilla has stopped updating facebook container. The current production version will block instagram from Threads and therefore cause Threads to not work with the add-on.
A fix has been merged in the source repo, but Mozilla has not yet updated the published add-on so far. Therefore, I’ve published a fork myself since May 7, 2025.
My version is the exact version built from the aforementioned fix revision (608c8dc). However, as with any other unknown add-ons / authors, you should NOT be blindly trusting me. If you’re worried, you can also just check out that latest version and built one for your own use. I’m publishing mine so I can have it sync via Firefox Sync.