Biased gunfight outcome in RedSec

I think all players are going through this issue, which is about how gunfights have different TTK results — sometimes we have to shoot three times more to take down an enemy. Why?

It’s not just spread/dispersion, I’m sure of that.

Another thing: I notice this always happens when PS5 DualSense and PS5 M&K players are playing together.

Why?

When will there be matchmaking between PS5 DualSense and Xbox controller