With all the toxic keybusters who either bail right after the key is activated, or bail later, there needs to be a severe Deserter debuff (2+ hours) for leaving a Mythic+ run. The problem is that there are legitimate reasons to end a Mythic+ run.
I propose a system like the vote kick, but where someone can vote to end the run. If at least two other players vote to end the run, or if someone has already bailed on the run (and gotten the Deserter), then the rest of the players can leave without penalty.
The reason for the vote option is so nobody has to take the Deserter debuff if the whole group decides to call it.