Comment 3 for bug 1928674

How can you introduce conffiles in grub-efi-amd64 & grub-efi-arm64 which is shared across releases? If in later series they have been removed from said package. That will cause a mess in focal+ then, since it will conflict with grub2-common there.

Given that the future is for these conffiles to live in grub2-common, it might be easier to backport the move from grub-{platform} to grub2-common.