There was a law passed that allows ISPs to block sites that host copyrighted content illegally. It's not just Italy, also the Netherlands and many other countries. You can still access it with a vpn or tor. Tor browser on the phone works fine for mobile carriers that block the sites.

Yes that seems to be the case - the blocking page is headed with "Ministero dell'Interno - Dipartimento della Pubblica Sicurezza - Direzione Centrale per la Polizia Scientifica e la Sicurezza Cibernetica - Servizio Polizia Postale e Sicurezza Cibernetica" along with official looking government logos but text underneath (in Italian and English) talks about a collaboration between govt agencies and ISPs. From mobile cell service it was not blocked.

The text does however mention it's a specific measure against child pornography, not re-hosting copyright content.

You don't even need a VPN. Just replace ISP's DNS servers with, say, Cloudflare's

    1.1.1.1
    1.0.0.1

or maybe OpenDNS's.

[Edit: fixed wrong fallback address.]