You can look up the AS and other info, like detected proxies or VPNs, using the form on https://iplocate.io/what-is-my-ip (disclaimer: I've run this service since 2017).

If they come from a consistent AS, you can block the AS. If they're using a proxy or VPN, you could try blocking those. If you don't expect to get traffic from hosting providers, you can block where `asn.type == 'hosting'`.