Suppression is one of those things that has as many answers as there are games 🙂
Some games have it as part of the dice results (Stargrunt), some build it into the activation mechanic (A freebie set called Slammer did this), some have it as a side effect of combat (Necromunda), some have it happen automatically (my own FAD rules)
The idea of “self-suppression” like in FUBAR and Forge of War (I think it was called) is a neat twist too. For my FiveCore game, it’s a separate die rolled. (You roll Kill and Shock dice when you shoot).
Nordic Weasel Games