The version 108 and 108.1 did the same, once you come down at IG entry number 10 or something suddenly Firefox hops up back to the last video even if you stop the video and btw you don't want to see it. Grabbing the scroll-bar and tearing it down helps a bit. Then, some entries further down suddenly the page gets blank - some video-window may blink but disappears. I run mint-21.1 and now i simply installed Konqueror so I can read IG w/o troubles.
