Hi Nabil.
I took a look at the thread you referenced.
Indeed, if I switch to a x11 session Salome runs fine and all the GUI buttons appear to be working.
So, the problem is apparently wayland. I am quite surprised to be the only one having this problem, as wayland is now the standard with debian 12.
However, thank you very much for the suggestions, you helped me a lot.
Andrea
P.S.: for reference,
here it is explained how to switch to x11 from wayland in a reversible way.