To avoid having a .it domain blocked for 5 days while changing the ns fields (probably while moving it from 2 registar) make sure to insert all the NS into the NIC (Italian DNS authority) DNS test https://dns-check.nic.it/. When the test is good, do the change.
When blocked a WHOIS of the domain will return
Note: the DNS check will try regularly for 5 days, then will revert back to the previous value of the NS field.
A longer blog post explaining the same https://www.dropcatch.org/change-of-dns-on-it-domain.html