I don’t know whether you are already preparing for the next, “bullseye” debian 11 release (“due” for next summer). Anyway, I think this could be interesting, unless it’s a temporary bug.
I played around with a KVM Whonix-Workstation 15 VM (don’t remember exactly which version, from last summer probably) that I fully
apt dist-upgrade to bullseye.
There must have been some changes regarding how
grub.cfg is generated, as it now seems to need
GRUB_DISABLE_LINUX_UUID="true" set in /
etc/grub.d/11_linux_live in order for live-boot to find and mount the root filesystem.
By default, not adding this parameter would produce the following kernel command line (I am quoting only the beginning here) which fails to boot/hangs/kernel panics:
linux /boot/vmlinuz-4.19.0-4-amd64 root=PARTUUID=41414141-01 ro single
/boot/vmlinuz-4.19.0-4-amd64 root=/dev/disk/by-uuid/26ada0c0-1165-4098-884d-aafd2220c2c6 ro single