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 this unpleasant effect. I assume the high resolution portion of your eyeball isn't used for motion inference, which makes sense.

I'm thinking this feature is exploiting this same peripheral vision cue.