My wife and I took our nephews to an indoor minigolf for kids. It's dark and purely lighted by bluelight. The S8 was the only screen that looked like this. G6 normal, iPhone, normal.
I thought the same thing about the always on display. However the LG G6 DOES have an always on display and it didn't have the same effect. I'm not necessarily worried about it. I was just curious as to what it was.