the csam problem is a fediverse problem. not just a mastondon problem, let me just say i am one of the most vocal critics of mastodon after running an instance for 5 years and running. but its unfair to call it a mastodon problem, mastodon is just a fediverse client. the csam can come from any fediverse peer.

but it is indeed a problem, and mastodon mirrors all remote content that is in your federation network and now you have csam splattered across the connections of mastos w only blacklists if entire instances to recourse.

its a bad approach but they've buried head in the sand years ago. things like pleroma do not do this by default