It’s not applicable, period. In PvP games, if you have a leaver or a troll, the game can just naturally end in a few minutes by the opposing team winning. A M+ run can continue as long as the servers are up so it’s always going to be a grief fest of who leaves first.
There have been propositions about a voting system to end a run, but even that has a major drawback in the ability of holding randoms hostage in hopeless runs, and you need only read threads like this one to see that there are plenty who would be happy to do so.
This topic has been popping up at least monthly on this forum for years, and I have yet to see a proposition for a leaver penalty that doesn’t have major griefing potential that results in even greater waste of time than simply having someone leave a group from time to time.