Firefox’s Enhanced Tracking Protection (Strict Mode) is known to cause issues on x.com
There were no “issues”; everything was working completely fine. This is a deliberate decision to force people to turn off tracking protection.
I saw a recommendation to use Firefox’s container extension https://support.mozilla.org/en-US/kb/containers, but it’s disabled in private browsing windows, and I always use private browsing windows.
I’ve found a fair amount of strong loyalty to the place from all sorts of people. I was never a twitter person, so I don’t understand it, but AFAICT, all sorts of people have a real emotional bond to the place, like for them it’s been their main internet experience in life or something.