Feed gets randomly filled with new posts

When going through the post feed, I'll randomly get 5-10 new posts added to the top of the feed. These 5-10 posts are all new with 1 or 2 upvotes only. Sometimes all from the same community.

This happens on local, subscribed, or all feeds. It also doesn't matter what sorting option is selected.

Is this a known issue or an expected behavior?