Comment by KerrAvon

The presence tracking technology in Face ID iPhones uses infrared beams (not sure if it's the same as what's in the Vision Pro), and some people's eyes are in fact sensitive to this, resulting in eyestrain when used over a long period of time.

You can turn this feature off to get standard idle lock screen timeout behavior, and still continue to use Face ID; I don't know if there's a workaround on the Vision Pro)