The 2019 Subaru STI S209’s stock brakes seem to have a darkened section which I believe is meant to provide a shade effect around the brake pads, however this texture is attached to the disc itself so as you’re driving along the dark spots spin with the wheels.
In the image you can clearly see a blackened out piece of the disc along the left side. As you drive this dark spot will freely rotate with all four of the wheels.
Windows 10, though I suspect it isn’t platform or graphics dependent.
The Varis widebody kit was installed on this car, I have not yet checked if the issue is present when unmodified.