Same it has worked fine for me for ages with Ublock, but this week it has been _bad_. I recently switched to 5g for home internet (i live in the woods), and thought that was the cause. But seeing others complain about it leaves me to believe some Google Manager is upset that people are A. blocking ads, and B. using Firefox.
I have occasionally run into a weird issue when I jump from one video to another - Video 1's title, comments and description (and maybe its recommendations?) will be displayed but Video 2 will play in the container. Load times are also wonky, but that's about it.