In VR, it's well known that your peripheral vision is a cue to your brain to infer motion direction. You can give yourself serious motion sickness in VR if you grab hold of the VR camera and force a roll / pitch in this state. One of the things some games do is during motion create "tunnel vision" when you move, shrinking down the size of the video feed and putting a black border around it. This significantly reduces…
Using tunnel vision to blunt motion detection is a clever way to reduce VR motion sickness. It never clicked for me why VR games did that until you brought it up