Yes, it's a new mechanism. I don't know how it's coded, but it's probably in armours.
I haven't played with this option yet, so I can't comment on it. I don't know if it's good or not. Regardless, when the first reaction to a new balancing feature is 'how do I turn it off', then I think it's not a healthy approach - unless it's a really, really BAD feature. But then it should be improved, since just turning it off looks like a straight up cheat code to me.
So what's wrong with it, and how to make it better?
Yes, it is in armors, probably with these negative recovery values.
The problem I have is the following:
I do not understand what it is good for.
I have some unconscious enemies lying around which die "seemingly" randomly. I have no possibility to check if they will die or not. What should I do to prevent this? Try to heal their stun damage and if they wake up stun and heal them again ... spiralling downward in a never ending circle of tediousness?
Maybe this feature was introduced to prevent "mass stunnings" which is ok, but than it would be better to choose another mechanism: Possibly that all stun weapons do some additional random health damage or something similar.
Anyway, thanks for the information, I will probably switch it off. Maybe other players will enjoy the feature.