smilem
It was a huawei matebook d15 laptop with windows 10 20h2. The screen was tv156fhm something from boe.
The reason I thought it worked is because the banding was extremely obvious on windows default wallpaper.
Put the default wallpaper as your background.
Launch ditherig and see if the image changes. For me the image was perfectly clear and after ditherig, banding was evident.
But I still noticed screen motion or flickering after. I think the app is not perfect, it could for ex disable intel gpu dithering but the screen could also dither by itself.
Especially I've always had problemd with screens from au optronics. I already wrote a post saying that I avoid them cause they triggered symptoms on a laptop while other screens in the exact same laptop didn't. That's why I thought they have some dithering by by themselves.