We are farm administrators of a SP2016 enterprise on-premise farm. We added some power users to "XXXX Owners" SP group which have "Contribute" permission. "XXXX Owners" is the group owner for all respective SP groups so that the power users can assign other users into different SP groups themselves.
However I would like to restrict them from modifying or adding Permission Levels to prevent them from changing SP groups' permission level to "Full Control". How can I do it?