Steps to replicate:

1. Upgrade to 1.5.10.
2. Open a chat with some history.
3. Scroll up at all.

Expected result:
When you stop scrolling, the window stays put.

Actual result:
When you stop scrolling up, after a couple of seconds (presumably network delay) the scroll position changes. Scrolling further causes more unpredictable jumps around. It's sometimes hard to get it to scroll to a particular position and stop. It' sometimes hard to get it to scroll back down to the bottom.

Note:
If I disconnect from the internet before scrolling up, this doesn't happen, so I think it's probably related to message history loading. History loading has always been a little janky but at least in previous versions it didn't get triggered until I had scrolled all the way up.

macOS 10.15.7 (19H15) on MacBook Pro (16-inch, 2019)