I think I got it working, following the suggestion to first update virtio drivers.
More here:
https://forum.proxmox.com/threads/windows-10-guest-enable-secure-boot-after-install-with-old-efi.98646/
Hello,
I'm having the exact same problem. I have to replace EFI disks on a bunch of Windows servers 2019 because of this:
https://forum.proxmox.com/threads/kb5012170-fails-to-install-on-win11-host.113561/