Probably OT but a bug that's been driving me crazy for a while now. When I open Instagram it reloads the feed every time as if the app had been purged from memory. This means if I accidentally close the app and reopen it my scroll position is lost and thanks to the sort algorithm the feed order has changed and I can't get back to where I was.
See this every time. Also on iOS if you have the app open, lock the phone, and then unlock you will be at the home screen. Almost as if the app ran out of memory or crashed in the background.
To me it seems like the feed is deterministic, that is, even between refreshes it stays the same, and when there are new posts on the top the old ones are still in the same order.