Thank you, that was it! I have blocked lemmy.ml around the same time, after unblocking it the issue seems to be fixed!
The fact that the blocking wasn't 100% and lemmy.ml still sometimes showed in the feed is also a bit of an issue, but that one didn't break the site in any way, so whatever and hopefully it will work properly in the future.
I am quite new to Lemmy and I don't yet understand specifics like this, so that may well have been it. Thanks.