Please force the scrollbar in the activity feed to be always there.
I have recorded a short video which explains why better than I could hope to with mere words.
that's the intended behavior
I don't doubt that, but it sucks. I implore you to reconsider.
Here are two more examples of the ugly interface glitches you get with these auto-hiding scrollbars throughout the site. The first shows the view when not hovering. When then trying to click the previous game and hovering over that exact window, without scrolling up or down, the second view appears where suddenly everything shifts and moves etc.


More generally I do not understand the seemingly arbitrary choices for hiding/showing scrollbars. Leaderboards, chat rooms, move lists: always visible. Timeline, game list: always hidden.
And at least the scrollbars could be hidden in a width-respecting way, as explained e.g. https://stackoverflow.com/a/33264668/1299188. Same effect, but no annoying glitching layouts.