Is it intentional, bug/glitch or cheat?

I’ve noticed something weird: sometimes I take all damage at once in a single tick, I’m running full health + shield and immediately get knocked out as soon as I take damage—often right at the very start of actual shooting (0.5 – 1 sec). They’re firing ammo-based guns that should chip away at my HP slowly, but there’s no instance of gradual damage per bullet. There are also times when I’ve been behind cover for half a second and then suddenly take damage through the wall (or with delay). My ping in-game is 50–70 ms (normal ping to Frankfurt is around 40 ms).

My question: is this some new server optimization feature—delaying and batching packets into one in a shooter game (where everyone, including you, brags about tick rates), which is “brilliant” in its own right…? Or is it a bug you’re not aware of, or some new kind of cheat? I’ve also encountered players with laser-fast sniper rifles firing 2–3 shots per second (no charge delay) doing full damage—even headshots for 175 (or more)—and if they don’t kill you, you can’t even report them. I wouldn’t be surprised if there’s a cheat that either creates the delay itself or exploits your “optimization” (if it’s your doing), sending one packet that says “all HP removed from a single hit” as soon as the cheater lands one bullet (no aim-assist needed—just one hit from a high-rate-of-fire weapon kills).