Is it cheating or bad design?

If you are a controller users, all I can say is tough s**t! It is by weapon damage and hit location. FYI, mouth and neck are NOT headshots in this game. You have to hit upper head, so in the face may have 2 different damage values. You should know the .44 is a 2 shot kill just about anywhere on the body at close range.

If you are on PC dying to controllers like this, know that they have the advantage in every way. 

Netcode is their advantage.
Aim Assist is their advantage.
25% less recoil and 25% less bloom is their advantage.
Because of these, they can take weapon mods that cost less and get the ones that balance out the gun for them, while we try to control recoil mostly, which is... their advantage.

If it is PC on PC, netcode and ping matter (Higher wins).

EA IS A TRASH COMPANY! NEVER BUY THEIR PRODUCTS AGAIN!

They do not listen, they believe in controller superiority, they are greedy AF and don't respond to legit questions.

Noticed it since season 2 dropped, slow rof sidearms outgunning assault rifles & lmg's ect, pretty sure something is going on, see more & more players since season 2 running with sidearms & 1 hit killing.

When there is no spectate or kill cam and no ping limits, it's hard to know.

The thing about ping is that if everyone has a low ping, good. If everyone has a high ping, good. But if there is a big spread between someone with a 12 ms ping and someone with a 262 ms ping, there is a 1/4 second smear of time occuring on the server where it tries to guess which person should be credited for hits and misses. It affects everyone, not just an interaction between the lowest pinger against the highest pinger, but everyone in the server experiences weird decisions about what is considered the current realtime. Throw in packet loss and server and client lag spikes and variably high CPU usage, and all sorts of weird things happen. That's why you die around corners or get insta-killed against legit players.  If EA cared, step one would be a ping limit.

Cheaters. you can report them alll the time. Keep in mind if you play battleroyale mode the developers bowed to the cheaters so you cannot report them but you can make a video record.You should know the difference between aimbot and triggerbot both are cheats. This is the report page but again might be closed or moved.  

https://help.ea.com/en/help-tools/report-a-player/

Spelling mistake:  Developers of this game don't know how guns work, or are people just cheating and EA can't do anything about it?