Since Dec 2024, there is a compatibility issue with linux-image 6.12 and nvidia-driver 535.216.03.
#1089513 - nvidia-driver: crash in drm_open_helper on Linux 6.12.3 - Debian Bug report logs
It seems that the upstream was already fixed this issue in newer release, but not available yet on Debian sid.
If you keep installed linux-image-amd64 or linux-headers-amd64, it will be booted from 6.12 by default. Surely it will boot, but it still has the resolution issue. It can't be your daily driver.
Thus workaround is sticking to boot from 6.11 linux-image. As usually older image was listed in "Advanced options for ..." submenu, you need to explicitly choose 6.11 image during booting. In such a case, the changing default boot image is useful. (another option is just purge all 6.12 linux-image, linux-image-amd64 and linux-headers-amd64, but it's out of scope in this article)
See /boot/grub/grub.cfg and collect each menuentry_id_option.
You need to collect the following menuentry id.
- submenu menuentry's id (It might be 'gnulinux-advanced-.....') [1]
- 6.11 kernel's menuentry id which you want to boot by default. (It might be 'gnulinux-6.11.10-amd64-advanced-...') [2]
Then, edit GRUB_DEFAULT entry in /etc/default/grub.
GRUB_DEFAULT should be combination with [1] and [2] which is concatenated with ">"
e.g. NOTE: the actual value might vary on your environment
GRUB_DEFAULT="gnulinux-advanced-2e0e7dd0-7e10-4b58-92f7-518dabb5b547>gnulinux-6.11.10-amd64-advanced-2e0e7dd0-7e10-4b58-92f7-518dabb5b547"
After that, update grub entry with sudo update-grub.
