I'm booting on a Thunderbold disk (Samsung SSD Portable X5). It was working great with Ubuntu 21.04, booting on a NUC 9 NUC9I9QNX and Dell XPS 13.
Upgrading on Ubuntu 22.04 make Ubuntu stop booting right after the Grub, after "Loading initramfs", then showing "Out of memory" .. "Press any key to continue", and then Kernel Panic.
Disk is still booting on Dell XPS 13. Using MainLine to upgrade kernel to 5.17.5 but no luck on the NUC, still have the same issue. Old kernel 5.13 have the exactly same issue.
My guess is that the bug is not in the Kernel, but in Grub.