That's true, I've been directly laid off and fired without cause without tricks, but the salient point to me is that usually it's a futile and burnout-inducing mission to try and put in extra effort to attempt to avoid the impending outcome. A manager at any company could just be annoyed with how you responded to a question one time and it'll be burned into their brain to get rid of you. In retrospect, although there have been valid moments where my performance has suffered, it's rare for that to be the cause imo, especially if they really don't know what you do anyway. You could think you're a crucial contributor, and all it takes is oversleeping on the wrong day to screw you permanently.