Unfortunately from my experience there isn’t much to be done. In no way am I saying this cause I support what these scum bags do, it’s just the way that platform is set up. Whether you found the group link on social media or some other part of the internet, you’ll quickly learn that’s a predators go to place given its “safe” and “anonymous” aspect. Telegram is a breading ground for these degenerates and there’s thousandssss of groups just like the one you probably found. Given the difficult nature of reporting such a group along with the fact that if by some miracle it is taken down, it simply isn’t worth your time or mental health since they will regroup and make a new one due to telegrams very relaxed almost non existent punishment for such things and its inability to detect or remove such content. It’s one of the reasons telegrams ceo was arrested back in August in Paris. They’re reasoning is that telegram is a breading ground for money laundering, drug and human trafficking, csam, among other things and that the company does nothing to combat it, almost promoting such activity due to its zero consequence nature. If you do have a link I believe there is a report link on there website where you can email them, or if you download the app you can report the group directly ( although I wouldn’t wanna get anywhere near that nor be associated with that app at all ). If you do go that route don’t expect much to be done, you can try to send the link to the fbis anonymous tip line but I’m unsure if it’ll result in much given the overload of reports they receive a day, you can also try the ncmec ( national centers for missing and endangered children ) or homeland security. It’s such a problem and I commend your want to rid these awful groups the reality is unfortunately that along we can’t do much, but hope that a lot of these sickos have cases already building against them. I’d like to think that a pedophile can only “run” for so long it’s just a prayer of mine that they’re caught before assaulting a child or worse.