That is the Reachability view. It moves the screen down so you can reach the icons at the top. It is activated on most phones by double-tapping the screen. So apparently the SE2 uses a different method. I haven’t been able to find what it is, and I don’t have one so I can’t experiment. But for the X and later you swipe up from the bottom of the screen and pause halfway up. You might try that.
As you have been told several times, the app switcher DOES NOT SHOW RUNNING APPS. It only shows apps that you have used recently. NONE OF THEM ARE RUNNING, and there is never a reason to kill them unless they stop working. Killing then INCREASES battery drain and slows down your phone. So until you find out how to access it on an SE 2 don’t worry about it.