Hi Josep-Maria,
I have had problems with an HP printer scanner as well - an M29w. One suggestion that I was given that worked can be found at Hplip missing files .
The printer also worked after I did a fresh 20.04 UM install (nuke and pave method).
HP printers and scanners have become really problematic for reasons that are not clear to me. So, my suggestion might just be more noise. Good luck.