iPhone 16 Pro Max screen splits with black bar at top when I swipe up

I have an iPhone 16 Pro Max, and whenever I touch near the bottom of the screen and swipe up slightly (not a full swipe to go Home), the screen splits all the apps move downward, and the top part of the screen turns black with a small arrow in the center.

It looks like the screen is being pushed down, leaving a black section at the top. You can see what I mean in the sample image below (mine looks just like this).

Does anyone know what this feature is called or how to disable it?