Since I enabled secureboot then starting the PC when executing "opensuse 15.3"
grub menu option
then
a text window opens with an error message:

....
creating secret key ....
...
EFI_RNG_PROTOCOL ....
.....

Sorry, I don't know how to stop the screen to write the message.

In "messages" file there is this :

2022-06-01T06:51:51.991630+02:00 localhost kernel: [    1.731758]
EFI_RNG_PROTOCOL unavailable, hibernation will be lock-down.
2022-06-01T06:51:51.991630+02:00 localhost kernel: [    1.731761] Lockdown:
swapper/0: hibernation is restricted; see man kernel_lockdown.7
2022-06-01T06:51:51.991630+02:00 localhost kernel: [    1.731762] PM:
hibernation: the secret key is invalid