This is part of Spy's Stash, unreleased modifications.

This mod causes corpses to always stay in ragdoll mode. Default Payday 2 causes corpses to freeze after a couple seconds, this mod removes this action. Try this with ragdoll limit changes as well as ragdoll collision mods. This mod does not interfere with stealth, as upon character death, an invisible node is spawned (which is what enemies see).

This mod does not affect bulldozer corpses, everything else is affected.

Video demonstration:
https://www.youtube.com/watch?v=Mn_xdJtT8Ko