Mettle of Man isn't usable
Before this thread starts, yes I'm aware of how busted OP MoM was on release, I don't want to go back to that. Also, please refrain from the whataboutism. The problem is with the prerequisites. If I can't heal without the killer making a mad dash for me, I can't get the perk to activate. On top of that, I can't get downed or I have to start all over again. The perk simply has too many activation requirements for it to be useful at all. If they just got rid of the aura reveal on healing, it could be a good perk.
Or they could just rework the perk entirely to something like this:
"Taking a protection hit for a Survivor gives access to the self-healing action for 40/50/60 seconds. The timer is paused while being chased and for 15 seconds afterward."
This takes away the abusable endurance effect while giving an incentive to take protection hits, and the pause on the timer is long enough so that you don't lose the effect when the killer loses line of sight at a jungle gym.