as you zoom in (with system zoom) it reduces the draw distance of z elevated objects
so objects in the distance begin to disappear, furthest first
in the attached cap, the objects are tinted based on distance
move around with the arrow keys, zoom in and out by dragging the blue box at the bottom
you can tell by the box tint that it's the further boxes disappearing
arrow keys move in 2d, dragging blue box adjusts depth, zoom in to see further objects disappear