Body of posts getting cut off at random

Hi, I've been having this problem intermittently for a few years and it's finally gotten under my skin. Using Firefox on desktop PC with privacy addons: ublock origin, sponsor block, and Ghostery, plus a few other random stuff like AI content shield and the one that restores the youtube dislike counter. Basically, when I open a post (in a new firefox tab or new private window), it will sometimes show the body of the post for a single video frame before removing it, so the very top of the page is the box for adding a comment, and I can't scroll up further. Refreshing the page with F5 will show the post body for another single frame before removing it again. Very rarely on refreshing it'll actually show the whole post body.

It doesn't always happen, but it has been getting more frequent lately. Googled this problem a lot over the years and never saw or heard of anyone else getting it. Anyone think one of my addons is causing this? Gonna test turning off extensions one at a time, but ublock origin is basically mandatory for using the internet these days so that one's staying no matter what.

Thanks in advance.