The distinction between base stats and temporary enhancements, which decides who leads Carl and Donut's party.
Carl articulates the rule while arguing with Princess Donut: all this stuff is based off base stats. Because the Cloak of the Benevolent Champion's description states the wearer loses its benefits over time once it's removed, the Constitution it grants is an enhancement rather than a base stat — meaning Donut's climbing Constitution can never reclaim Party Chat leadership from him no matter how high it goes.
Donut's response is that she doesn't even know what that means and it sounds like Carl is making it up, which does not stop her from immediately invoking his new authority to complain about Rend.
Underlying stat rule that permanently settles the party leadership dispute.