I’ve just now noticed this because of all the new posts flooding in. When you have a post enlarged on the feed (without going into the comments page), and a new post appears at the top when sorting by new, the view abruptly shifts to the top of the page and you lose your spot.

Another bit of feedback – I do miss how on Reddit (new Reddit, I never used old), when you click on a post and read the comments, the feed remembers your spot and when you click off to the side you’re back where you were before opening the post.