iOS was helpfully responding to both events, which made it look really, really weird to have both a menu sliding in, and the back/forward event swiping in the navigation.
iOS and windows phones no longer should have any issue here as the swipe in events are android only now as of here:
https://github.com/discourse/discourse/commit/c3cbff55be527a95b016b6057fa04dbf8804dbcc
re: accidental swipe in, it looks like 30px for the swipe space was a little too large as a swipe target. I’ve shrunk it to 20px, and am unable to reproduce accidentally opening a menu when liking, or clicking on like numbers or – what I’m assuming is happening with quoting – tapping and holding on a post, and dragging the finger horizontally to select text (I never actually knew you could select text that way – I’ve always doubletapped to get the selection pins). Anyway, that should be better here 
https://github.com/discourse/discourse/commit/d997b01a24456cbeaa98db9fc0315e2d7ea33141