From the blog post: If your 1200 × 800 window is set to be scaled to 125 %, with the unified renderers, we will use a framebuffer of size 1500 × 1000 for

From the blog post: If your 1200 × 800 window is set to be scaled to 125 %, with the unified renderers, we will use a framebuffer of size 1500 × 1000 for it, instead of letting the compositor downscale a 2400 × 1600 image. The explanation is a bit confusing to me. I think they are saying that a window that should be drawn as 1500 x 1000 pixels on the screen because of 125% scaling would have 1200 x 800 pixels in application pixels. Since OpenGL and Vulcan use floats to render, they might as well render directly into a buffer that can be rendered 1:1 on the screen by transforming the coordinates in the instructions. If that's what they are doing, that sounds like sanity finally.