Hi @Andrea_Baldassi ,
welcome to the ROOT forum!
This is a known problem with latest-stable/v6.26.02. You should find several hit on the forum, e.g. Error building ROOT from source on MacOS 12.4 - #2 by eguiraud or Installation issues ROOT from source on Ubuntu 22.04 - #3 by eguiraud . It is fixed in the master and v6-26-00-patches branches, and it will be fixed in the upcoming v6.26.04 patch release.
Cheers,
Enrico