Enemies (NPC) Deal more damage in DZ sometimes and i need more bullets zu take them down??!

Its very Strange

Sometimes i Need a lot more bullets to take enemies in DZ down but the damage i get from them is enormously like i only have 40k health and my armor is at only 20%.

My friends noticed the same and was wondering how fast a enemie (npc) can take us down and that we dont Deal the damage as usally...

Anyone else noticed this?