There is a subreddit sharing explicit pics of a minor, but Reddit won’t remove it.

I won’t share the subreddit for obvious reasons, but it’s bad. I moderate an nsfw subreddit, and I took down a post for having a young looking person in the picture. The person that reported it initially found the girl’s instagram and a subreddit about her. It is obvious from her posts that she is 17 and in highschool, and the 1,000+ members of the subreddit know it based on their comments and posts. They had a discord which got banned over a week ago, and now there is a telegram group. Every day that this subreddit stays up, more and more pedos have access to that group. When reporting any post on that subreddit, there is an automated response saying that it has already been investigated and doesn’t break Reddit’s rules. That sub needs to be banned immediately, but the reporting system isn’t working. What else can I do?