When reading posts sorted by date, I often have the timeline import a whole bunch of old posts from one community at the top. This is annoying since I basically have to reload the page, otherwise all relevant content is gone.
The new sort is pretty important, since Lemmy doesn’t have a lot of posts anyways.
I’m not sure if this is the same issue, but sometimes I’ll be browsing posts by new and a bunch of months old posts will be fetched for no apparent reason. This happens to me occasionally, but unfortunately it happens seemingly randomly, so I don’t know how to reliably reproduce the issue to find out what’s causing the problem.
I share this experience. It’s really annoying.