Whenever I try to upvote a comment, I get this warning and the upvote does not take effect.
When I try to upvote a post, I don’t get a warning but the upvote also does not appear.
This happens both on the web interface (Firefox with extensions, also tried in stock Firefox and got the same result) and in the mobile app I use (Thunder).
AFAIK it started maybe three weeks ago? Not 100% sure cause I was off Lemmy for a bit of time.

A quick startpage search yielded no useful result… Any idea on what could be causing this behaviour?
Let me know if I need to provide more information for troubleshooting.