Bootloader (grub) configuration for 12.1 installation is set for grub loading from MBR.
What means then Yast2 warning message
“Selected bootloader location MBR is not on /dev/sda any more”
w/proposal “Set default location ?”
And btw, what is the target of Harddisk section in grub configuration file ?
So, as to the error message, if you elect to load the MBR with Grub of a disk that is not designated as the first disk in the booting section, then you get this error. For grub to work, it has to be loaded on the selected boot disk, which is most often /dev/sda. If you are selecting a different disk as the boot disk in your BIOS such as /dev/sdb and loading grub onto that disk and intend on selecting as the first boot disk in your BIOS, make sure its selected as the first disk in the openSUSE booting section before you allow the installation to continue.
So, if you have but one hard drive, then the error message means nothing. As for the "map (hd0) (hd0) " this is BS and can be removed, but does nothing useful or bad if it remains. I do wonder why the installer is coming up with this stuff on your system?