Last week, my favourite German lawyer Udo Vetter made a blog post [1] about parents reporting questionable media in group chats to the police.
He warns urgently to never do this.
If you're in a large telegram group, discord, WhatsApp or whatever, and your phone downloads the questionable media automatically, you're already doing a crime (the mere possession of such media is illegal). In Germany, the minimum punishment for the possession of child porn is one year; a monetary fine is not possible and a dismissal of the case due to insignificance isn't possible either.
According to Udo Vetter there have been cases where "concerned parents have brought printouts of the chat messages to the police so that the things are not distributed further. Criminal proceedings for possession of child pornography were the result."
Further down in the blog post how there were funny cases like the police seizing a mobile phone of a drug dealer, and then finding group chats with thousands of users where questionable images were shared. Which will then start a mass investigation on thousands of innocent people, who weren't even looking at that stuff. No one looks at group chats 24/7, especially in fast-moving chats with like 10 messages/minute.
The issue isn't even new. I remember many times when IRC networks were flooded with such media by troll collectives like myg0t, 4chan and whatnot.
[1] https://www.lawblog.de/archives/2023/05/12/lustiger-gruppenc...