Just looked into it a bit more, turns out they're still working, but:

RD received a formal notice from the National Federation of Film Publishers (probably law suit) so RD has to comply and strengthen anti piracy measures.

That started with the deactivation of the API endpoint /instantavailability which is what 3rd party app add ons like torrentio and Fen Lite/Cocoscrapers used to scrape streamable cached links (I think)

The notice also included a blocking of torrents and purge of the cache of specific media, we don't know the full extent of this yet but it seems many links are already being blocked

The reason torrentio is working with RD again is because the torrentio dev built a workaround so that it will still use RD to pull links we just aren't able to see if they are cached or not, I do not know if this is a permanent fix but as far as I can tell, things will continually get worse for RD, not better.

Reddit

Non-Reddit link

Seems like this explains it pretty well, though Stremio has basically an app for every device, not only the firestick:

https://champagne.pages.dev/piracy-guides/firestick/#stremio--trakt

Also, I don't remember doing the "Trakt" part when setting up, just used Debrid and Torrentio to connect it to Stremio.