dkms is a little finicky. If a kernel version fails building his modules the whole think borks and it doenst build modules for 6.11 afaict (i cant boot into 6.11 either with same sympthoms)
Basically another workaround to get your system to boot back is to simply purge linux-headers-6.12.6-amd64 and reboot to 6.11 Cheers
