I tested this and I did not got blocked or anything. https://www.threads.net/@mogoh_viol/post/C4xsvpKMZb8 So I assume, this was just an accident.
I know everybody loves to hate meta, I am am not a fan either, but I find it hard to belive that they outright ban the word pixelfed.
No no no! You got it wrong! It was because checks notes Imperialist USA!