From what I can tell, it looks like your registrar's nameservers (ns1.register.it, ns2.register.it) are sending an invalid DNSSEC signature when querying for your domain's CAA record.
That's a lot of jargon but I think one of the following might work:
Creating a CAA record for your domain could work around the issue by avoiding having an NSEC response
Disabling DNSSEC for your domain at your registrar, which will avoid signature validation
Contacting whoever runs register.it and asking them to rehash (create DNSSEC signatures) for your zone.