I also see it with any number (>= 1) of eyes open and at any angle. Wonder if GP's phone was on night shift or something similar - the article mentions that color changes impact the illusion's visibility.
Interesting, I have astigmatism so I tried it without my glasses and with both one and two eyes open at different angles and I still see the illusion (with no change in intensity of the “bobbing”)
I also see it with any number (>= 1) of eyes open and at any angle. Wonder if GP's phone was on night shift or something similar - the article mentions that color changes impact the illusion's visibility.