@cactux thank you for your suggestion.
Unfortunately this did not solve the problem.
NOTE: the entries in systemd-boot contain “nomodeset“. I suppose this is because when I created them, the kernel was loaded with the “nomodeset“ set.
What annoys me the most is that even with live USB installations, I cannot boot without using “nomodeset“.
I am really confused.
But thank you for trying to help.
Salvo