I tested the patch with a fresh installation of: 1) Leap 15.3 with self_update=1 and using online repository (to ensure I was using the last update of the grub package) 2) Leap 15.4 beta 222.1 Secureboot was disabled in bios and NOT selected in the bootloader configuration and everything has worked as expected in both installations. From my point of view the patch has solved the problem. Thank you very much!