As said, I took the new kernel out of our APT repo for now, so it won’t break anymore after first boot updates.
The Debian version (Bullseye vs Bookworm) ist generally irrelevant for all but x86_64 and RPi images, as they ship with the same kernel and bootloader builds, being distro agnostic.
We narrowed down the Linux version which broke it, but I need to find time to check the commit logs.