The article claims this is what the ZKP scheme reveals:

> Here is cryptographic proof that I hold a valid credential proving I am over 18. You can verify the proof, but you learn nothing about who I am.

Is this true though? I am genuinely interested as I haven't looked into the details, but must the user not at least also disclose who the issuer of the credential is so the verifier can verify it against a public key? This also reveals at least the nationality of the user and could be misused to block access to foreigners using VPN.