This issue comes from the fact that even though the domain is now changed to x.com, it still tries to load content from twitter.com which Firefox thinks is social media tracking because it's coming from a different domain than the one you're on.
It's a hilarious and dumb oversight with this change.
One of the managers in my org used to work there, and lost his job post-takeover. Apparently most that were left were on L1B visas, so had no opportunity to move elsewhere. His theory was that Elon knew exactly what he was doing, because he now has a team of engineers in their late twenties and early thirties that'll basically do whatever he wants, or risk uprooting their families back to their home country.
They're probably still great engineers, but when you're doing the job of multiple teams, or things have zero coverage, shit is going to slip.