My guess is another CSAM attack. In case you weren’t aware, there are some bad actors who will occasionally use AI to generate CSAM, then post it on any servers they can find using bots to get things to the /All front page.
And since instances are usually just run by one or two people, response times can be long. Because the instance owner won’t even know anything is wrong until they log on.
Many instances defaulted to disabling image posts to stop attacks in the short term, so the admins can work on scrubbing the existing posts and banning any users that posted it.