Right now, the only recourse for reporting individual cheaters outside the game is to send a private message to CG_LucifersDaddyMINI. I am closing this to that end; however, am moving this to feedback in line with OP's general concerns of it being a potential issue with the new changes.
As for what you may be seeing in the leaderboards however, there seems to be a bug that is currently placing players who haven't logged in and don't have a skill score at the top of Kyber. If you look, they don't meet the GP requirements for those leagues. In theory this should drop once they log in and as GAC starts and skill scores change.