Comment # 6 on bug 1137061 from Neil Rickert

"grub.efi" has to be a one-size fits all.  It is digitally signed at build
time, so cannot be adapted to a particular install situation.  And there is no
"btrfs" subvolume for people not using "btrfs".

By contrast, the "grubx64.efi" (which is a copy of
"/boot/grub2/x86_64-efi/core.efi" is built at install time as part of
installing grub2, so it is adapted to what you need.

Yes, I agree that this bug should probably be closed.  But I prefer to leave
that to someone from the openSUSE development team.  Perhaps they need to add a
more detailed description as to what that "secure boot support" flag does in
Yast bootloader.