So if one does the wim hof breathing, or any hyperventilation basically or overbreathing, and then forces pressure from chest to neck to head, they will see some strange lights - very unique phenomenon that I have recreated over 100 times now.

I can't figure out what it actually is or find any scientific observations explaining the phenomenon.

Any input is greatly appreciated!

Maybe it's pressure from behind the eyes that somehow stimulates these observable effects?

Cerebral noise?

It's the same kind of light one sees when pressing on their eyelids, or when on the edge of sleep, isn't it? Interesting stuff.

Related or identical https://en.wikipedia.org/wiki/Phosphene