Comment 9 for bug 1943097

I'm also experiencing this after the latest 21.10 update on two builds on the same Raspberry Pi 400, booting from USB. I added a comment on https://bugs.launchpad.net/ubuntu/+source/linux-raspi/+bug/1937924 which sounded similar. I have restored a bootable system by mounting the devices on another machine and replacing initrd.img and vmlinuz on the boot partition with the .bak versions.