There's no such thing as a subpoena in the UK, just equivalents. I guess you translated it for an international audience, but can you clarify exactly what Cloudflare received? From what court? What did it require them to disclose?
Cloudflare do not guarantee protection against your identity being discovered when the law is involved, they are not a service for anonymity against the law. You will need to make peace with your identity being revealed. Although too late now, there are other options for publishing online with anonymity.
Cloudflare do not guarantee protection against your identity being discovered when the law is involved, they are not a service for anonymity against the law. You will need to make peace with your identity being revealed. Although too late now, there are other options for publishing online with anonymity.