So I'm running a homebrew campaign and one of my players somehow got 4 levels higher and about 40 extra hit points than they should. I don't want to call him out on it and waste precious time explaining everything. Is there a monster that is made to counter rogues? Maybe a disease? They are the only rouge and they are very convincing to everyone else, but I'm onto them. They are level 14 now while the next highest level in the party is 10. I just need to find a way to stop their health increases because they are about 20 health above the barbarian.
The party does not share experience. The rogue, (in encounters) keeps complaining about how I "nerfed them" because I thought evasion and uncanny dodge were op and limited them to 5x a long rest. My argument is that they are basically a barbarian now, with all the extra hit points, but they only have 12 constitution.