I have. similar symptom in a completely different environment:
- Arch Linux Host
- Arch Linux Guest
- Guest with systems-boot and efi-stub
- Guest with auto-detected efi partition
Symptom is, that after downgrading and re-upgrading the kernel, the reboot will hang, similar to what Daniele Credo reported.
Everything is fine, if mounting efi partition statically, i.e. via fstab.
Downgrading to 2020.11 resolved the issue.
I have a setup available that can reproduce the issue, since I narrowed it down already.
Let me know if I can help in any way to identify, and hopefully fix, the issue.