Here, if any pair of countries have conflicting rules then you simply can't expose your service to both because it's plain impossible for you to block all means of VPN/proxy regardless of how perfect your service tries to detect it. There's no payment, there's no account, there's no anything - you're just serving DNS to an IP that reports to be out of Germany according to German law. At some point it stops being a mistake/malintent of the company and one of the user. Where that transitions probably depends on the person though.