got this mod from Jadiepop (previously known as YourCryingFox).
the mod fixes the grace period, since sometimes grace didnt work properly

update:

Affinitive, a very good Payday 2 player told me today how the mod actually works:

"Mod originally made by a friend called Shavuz

The mod stops you from getting "graced" by always giving you the 0.35 second grace period. Usually grace works by having this timer but if the next damage you take is higher than the last damage you took then the 0.35 second timer doesn't apply.

It isn't a bug fix mod because this is intentional behaviour. Just some people complain about getting graced 3x+ by multiple units and instantly dying, so Shavuz made the mod for himself.
It's really more of a cheat mod by always giving you 0.35 seconds of invulnerability after being shot."

so, in other words, this mod actually buffs Grace by always giving the 0.35 seconds, even if a Heavy Swat hits you after a Light Swat.
As such, i have marked the mod as "Gameplay Changing" instead of QOL as i previously had thought