Please help! What is this corpse buff/soul harvest effect in PoE 2?

Hey everyone,

I've been playing the PoE 2 (Witch Lich), and I noticed a specific visual effect over corpses — dark shards rising up with some energy crackling above them. It only appears after I kill enemies, and seems to trigger some interaction. I think it's recharging my Energy Shield, but I'm not 100% sure.

It looks like the bodies are being consumed or "harvested".





P.S GGG support referred here, Discord - noone knows.