After opening the website, the newest posts shown to me were at least a month old. Tried clearing cache, cookies, etc. and didn't help. Posted something myself and it showed up at the top of the timeline. Unfollowing and refollowing the accounts I follow seemed to fix the issue, and return things to normal.
I also saw this. The unfollow/follow trick worked for me.
Posts from yesterday and today show up normally in my latest posts feed. However, the most recent post I have in my latest posts feed from before then is from mid-November. The missing posts (from mid-Nov to early Jan) are still on people's pages, just not showing up on the latest posts feed.