linux-6.9.4 monitor type/size detection fails for Dell box (6.9.3 is fine)

Description:

Update to linux-6.9.4 and now resolution is no longer correctly set to 1920x1080 for the console or X windows. The monitor (a Samsung TV 59") has always been correctly configured for full-HD using the built-in Intel driver for this older Dell box (Optiplex 360 running a Core2-Duo). I have run Arch on this box using it as a media center for years.

After update tonight, it no longer does that. Instead both the console (I use startx) and fluxbox (or any other desktop) boots and starts at 1024x768 -- which is quite unusable. This issue was first discussed on arch-general as "linux-6.9.4 or firmware broke monitor type/size detection for Dell box?".

The box is MBR and boots to multi-user mode and then startx is used to bring up the desired desktop (usually fluxbox). The grub config in /etc/default/grub has always been:

...
GRUB_TERMINAL_INPUT=console
GRUB_GFXMODE=auto
GRUB_GFXPAYLOAD_LINUX=keep
...

It has always just worked.

Downgrade to linux-6.9.3 restores correct resoluton detection, so this is a 6.9.4 new issue.

Additional info:

No custom configurations, xorg.conf is auto-generated, and grub uses defaults for booting to multi-user mode.

Steps to reproduce:

1. Update to linux-6.9.4
2. reboot
3. resolution no longer set at 1920x1080, but now set at 1024x768 for console and X.

The Xorg.0.log for 6.9.3 shows:

...
[  1035.029] (--) intel(0): Integrated Graphics Chipset: Intel(R) G33
[  1035.029] (--) intel(0): CPU: x86-64, sse2, sse3, ssse3, sse4.1; using a maximum of 2 threads
[  1035.029] (II) intel(0): Creating default Display subsection in Screen section
	"Default Screen Section" for depth/fbbpp 24/32
[  1035.029] (==) intel(0): Depth 24, (--) framebuffer bpp 32
[  1035.029] (==) intel(0): RGB weight 888
[  1035.029] (==) intel(0): Default visual is TrueColor
[  1035.029] (II) intel(0): Output VGA1 has no monitor section
[  1035.030] (II) intel(0): Enabled output VGA1
[  1035.030] (--) intel(0): Using a maximum size of 256x256 for hardware cursors
[  1035.030] (II) intel(0): Output VIRTUAL1 has no monitor section
[  1035.030] (II) intel(0): Enabled output VIRTUAL1
[  1035.030] (--) intel(0): Output VGA1 using initial mode 1920x1080 on pipe 0
...
[  1035.285] (II) intel(0): switch to mode 1920x1080@60.0 on VGA1 using pipe 0, position (0, 0), rotation normal, reflection none
[  1035.296] (II) intel(0): Setting screen physical size to 508 x 285
...

The Xorg.0.log for 6.9.4 shows:

...
[  5371.538] (--) intel(0): Integrated Graphics Chipset: Intel(R) G33
[  5371.538] (--) intel(0): CPU: x86-64, sse2, sse3, ssse3, sse4.1; using a maximum of 2 threads
[  5371.538] (II) intel(0): Creating default Display subsection in Screen section
	"Default Screen Section" for depth/fbbpp 24/32
[  5371.539] (==) intel(0): Depth 24, (--) framebuffer bpp 32
[  5371.539] (==) intel(0): RGB weight 888
[  5371.539] (==) intel(0): Default visual is TrueColor
[  5371.539] (II) intel(0): Output VGA1 has no monitor section
[  5371.539] (II) intel(0): Enabled output VGA1
[  5371.539] (--) intel(0): Using a maximum size of 256x256 for hardware cursors
[  5371.539] (II) intel(0): Output VIRTUAL1 has no monitor section
[  5371.539] (II) intel(0): Enabled output VIRTUAL1
[  5371.539] (--) intel(0): Output VGA1 using initial mode 1024x768 on pipe 0
...
[  5371.571] (II) intel(0): switch to mode 1024x768@75.0 on VGA1 using pipe 0, position (0, 0), rotation normal, reflection none
[  5371.576] (II) intel(0): Setting screen physical size to 270 x 203
...

All other lines are the same. I also have the dmesg output for both kernels, but everything looks the same. Let me know if you want those and I can attach them (I think) or post them somewhere or compress and e-mail to whoever needs them. They are a bit long to include inline here.

Any other information you need, let me know and I'll get it. Strange issue, but something broke.