GNOME/Mutter - Wayland Fractional Scaling Breaks VM Resolution
Description of problem:
VMs are rendered at a higher resolution than the pixel count of their window, seemingly because mutter is upscaling for fractional scaling.
Steps to reproduce:
1. Enable GNOME Mutter experimental fractional scaling
2. Launch VM
Additional information:
This only occurs when wayland fractional scaling is enabled, not when text is scaled. Since GNOME/mutter accomplishes fractional scaling by upscaling, I think the VM is being told its window has a higher resolution than it actually has, so it is rendering the VM at a higher resolution, which is then displayed at the display's real resolution.

In the screenshot below, my resolution is 2256 x 1504 and I have set fractional scaling to 125%. It is worth noting (2256 / 1.25) / 3606 is approximately 0.5.

![image](/uploads/0014f068f6491175c00449093c40cd8c/image.png)

I apologize if the report is unsatisfactory. I will provide more detail if instructed. I tried reporting to GNOME Boxes and Virt-manager, which both use QEMU, but it seems the problem is upstream.