This principle emphasizes that there should be no space behind you. It has nothing to do with the wall or window in front of you. Those are just examples I used to explain according to the original post.

If you're concerned about the window's position, ancient Feng Shui advised the window should be located to your side, specifically on the side of the hand you don't use for writing. I think their reasoning was: this way, your head and the hand you use for writing won't cast shadows on the area where you're writing.

Workplace safety rules for screen workers say that to avoid eye strain, windows should be to the side, not in the direction you're facing. On a bright day the light coming from the window can have an intensity multiple orders of magnitude higher than the screen. I find it very uncomfortable.

That’s usually bad due to the brightness contrast with the screen. The lighting of what you see next to the screen needs to be controlled, so that it can match the brightness of the screen.

It can be good natural light for video calls.

I like it to the side more, if it is in front you'd have to look from above monitors to see it.