Dying from no shots

How now am I dying from not being shot at all.

I can walk in a room shoot someone I can get die immediately as soon as a first shot is fired and report says there is exchange of fire.

Or enemies health completely depleting and not dying.

How can I be shooting an enemy in the back for half a magazine and they turn around and kill me with the same gun, no missed shots.

Getting shot through walls is fun too

This is with 44ms ping and 0 packet loss. Absolutely atrocious