You can fix that dumb issue with your feed jumping pretty easily. Just follow these three steps (Can't find the tweet that tipped me off, so apologies for the lack of a hat tip/RT) 
Hope it works for you, good people of Twitter. Worked like a charm for me but some folks are saying it doesn't stop the issue for them. Try restarting the app, and if that doesn't work just burn your phone and reclaim your life from this hell site 🤷♂️
Also, to be clear, "reduce motion" is NOT checked by default--where I wrote "check this" I mean turn it to "on." Hope it helps!
