There have been users spamming CSAM content in !lemmyshitpost@lemmy.world causing it to federate to other instances. If your instance is subscribed to this community, you should take action to rectify it immediately. I recommend performing a hard delete via command line on the server.
I deleted every image from the past 24 hours personally, using the following command: sudo find /srv/lemmy/example.com/volumes/pictrs/files -type f -ctime -1 -exec shred {} \;
Note: Your local jurisdiction may impose a duty to report or other obligations. Check with these, but always prioritize ensuring that the content does not continue to be served.
It is where scum spam a site with illegal images, which can result in the site being taken down and in some instances the site owners being prosecuted.
Depending on where you live you may have a legal obligation to report the incidents and to prove actions taken to remove the content.
related in the US: safe harbor laws