On mobile, and Chrome at least, a sliding down reloads the page, which is expected.
On Discourse, when you’re at the bottom of a topic, you’ll swipe down to show the above posts. When you reach the first unloaded post, then Discourse starts loading the previous posts thanks to the infinite scrolling (it goes both ways).
The issue is that if you swipe down while Discourse is loading the new posts, then Chrome reloads the page and sets you at the post you were at before.
It mostly happens if you swipe down aggressively.
I suppose I should be using the timeline for this, but sometimes I prefer scrolling because I get to see the posts’ contents while I scroll.