Comment 3 for bug 2040187

Same while testing again.

23.04 -> 23.10: upgrade works until grub is upgraded and reinstalled.
Afterwards UEFI will not find and load grub any more. Failing to boot.

If grub is not replaced (it is enough to pin it to the old version), kernel 6.2.0 will stay bootable, while kernel 6.5.0 wont boot.

If removing outdated packages after installation as advised by do-release-upgrade you'll have an unbootable system afterwards. If pinning grub and kernel too what was installed by latest updates to 23.04 the system will stay bootable.