byzantium: dracut does not build initrd files which provide disk decryption using the LibremKey
In Byzantium the initrd images in /boot/ are generated by dracut. dracut does not put the files necessary for decryption of the rootfs using the LibremKey into the initrd files.
The package initramfs-tools in the Byzantium repo does not contain /usr/sbin/update-initramfs. To me it seems uncomplete and/or broken. It is installed alongside with dracut which seems not to be possible in debian bullseye.
Installed initramfs-tools and initramfs-tools-core from the debian bullseye repositories. The dracut package has been deinstalled by this automatically. update-initramfs generated a initrd which included the missing files for disk decryption using the LibremKey and disk decryption using the LibremKey does work again like in Amber.