> He's also got Cleartype on and set to RGB stripe even though the OLED is not RGB stripe (though to be fair, Windows doesn't really make it clear what each page of the ClearType tuner does).

I doubt it's Cleartype, the close up photo of the U3223QE show all subpixels uniformly dimmed on the fringes. The post also says the monitor is attached to a Mac mini and a previous post about OpenSCAD has a screenshot with MacOS window decorations.