Windows: we can't just put your image as a wallpaper, we need to compress it as a 85% jpeg first. I know you already saved it as jpeg, but we still need to convert it before. that's how this works.
Linux: you want an avif or heif as wallpaper? yeah no problem chief. done.
@alyx
Huh... I can't believe I didn't notice this.
I use Ekko's splash art as my wallpaper and I can instantly tell if a display has sharpening enabled or if the aspect ratio or color balance is incorrectly set.
BTW, if you still use Windows, and care about your wallpaper, please do this at least.
https://techcult.com/disable-desktop-wallpaper-jpeg-quality-reduction-in-windows-10/