Possibly related to this issue which happened yesterday:
Are you still seeing incorrect counts in the app?
I’ve finally had some time to look at this. I can reproduce this if I play a video using YouTube’s embedded HTML5 player, then just tap any space outside the video. (Doesn’t even need to be a control, just the empty space will do.) There’s something that happens when that player loses focus that causes the scroll, but I haven’t yet isolated it. Neither can I explain why the web view behaves differently to Safari. Am still debugging through this trying to find the underlying cause.