Using QEMU 6.0.0 (compiled from sources) with PC BIOS and video

    -nodefaults \
    -machine q35,accel=kvm \
    -vga virtio -display gtk,gl=on,zoom-to-fit=off,show-cursor=on

I set resolution 1280x960 in grub (set gfxmode=1280x960). Kernel 5.13.6 retains
this resolution. Kernel 5.13.13 switches to tiny window with resolution 720x400
(I believe). No other changes in environment. Comparing dmesg output

5.13.6:

Sep 01 20:27:08 tw kernel: [drm] pci: virtio-vga detected at 0000:00:01.0
Sep 01 20:27:08 tw kernel: checking generic (fe000000 4b0000) vs hw (fe000000
800000)
Sep 01 20:27:08 tw kernel: fb0: switching to virtiodrmfb from VESA VGA
Sep 01 20:27:08 tw kernel: Console: switching to colour dummy device 80x25
Sep 01 20:27:08 tw kernel: virtio-pci 0000:00:01.0: vgaarb: deactivate vga
console
Sep 01 20:27:08 tw kernel: [drm] features: +virgl +edid -resource_blob
-host_visible
Sep 01 20:27:08 tw kernel: [drm] number of scanouts: 1
Sep 01 20:27:08 tw kernel: [drm] number of cap sets: 2
Sep 01 20:27:08 tw kernel: [drm] cap set 0: id 1, max-version 1, max-size 308
Sep 01 20:27:08 tw kernel: [drm] cap set 1: id 2, max-version 2, max-size 696
Sep 01 20:27:08 tw kernel: [drm] Initialized virtio_gpu 0.1.0 0 for virtio0 on
minor 0
Sep 01 20:27:08 tw kernel: Console: switching to colour frame buffer device
160x60
Sep 01 20:27:08 tw kernel: virtio_gpu virtio0: [drm] fb0: virtio_gpudrmfb frame
buffer device

5.13.13:

Sep 03 07:51:58 tw kernel: virtio-pci 0000:00:01.0: vgaarb: deactivate vga
console
Sep 03 07:51:58 tw systemd[1]: Reached target Initrd Root Device.
Sep 03 07:51:58 tw kernel: Console: switching to colour dummy device 80x25
Sep 03 07:51:58 tw kernel: [drm] features: +virgl +edid -resource_blob
-host_visible
Sep 03 07:51:58 tw kernel: [drm] number of scanouts: 1
Sep 03 07:51:58 tw kernel: [drm] number of cap sets: 2
Sep 03 07:51:58 tw kernel: [drm] cap set 0: id 1, max-version 1, max-size 308
Sep 03 07:51:58 tw kernel: [drm] cap set 1: id 2, max-version 2, max-size 696
Sep 03 07:51:58 tw kernel: [drm] Initialized virtio_gpu 0.1.0 0 for virtio0 on
minor 0
Sep 03 07:51:58 tw kernel: Console: switching to colour frame buffer device
90x25
Sep 03 07:51:58 tw kernel: virtio_gpu virtio0: [drm] fb0: virtio_gpudrmfb frame
buffer device

There is no "switching to virtiodrmfb from VESA VGA" line in 5.13.13. Full boot
logs attached.