Nah, once it become possible to group communities from multiple instances into one (aka multi-reddit on reddit - needs another name on the fediverse), power mods will have no power. Someone could just create an instance with the same community name and it could end up in the community group.
should we be worried about powers-moderators/users?
Power mods are one of the main problems with reddit. The same thing is already happening with Lemmy....