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.
People are still using that shit because other people they want to interact with are still using that shit. Network effects are hard to break.
I occasionally use it to complain at corporations, mostly when their websites show me captchas but occasionally for other customer service issues.