Collusion and Knowingly exploiting a backdoor hack on PokerBros

I have proof of 3 highstakes players on Pokerbros colluding to exploit a back door hack to see other players hole cards.
Player A informs Player B of a "Sick hack" that one of their friends, Player C has.
After discussion of the devices Player B has to perform the hack, Player B asks Player C for the hack.
Player B installs Pokerbros hack Player C shares with him. Player B installs PokerBros through Github. Not the verified installation platforms such as Playstore or Apple store...

How do I escalate this to the correct authorities please.

I am disgusted that this is happening and from such accomplished, well known players

Thank you