I’m not sure what you are saying I am mixing up.
The article links to the source code repository here:
https://github.com/eu-digital-identity-wallet/av-app-android...
That links to the tech spec:
> The solution leverages the existing eIDAS infrastructure, including eIDAS nodes and the trust framework for trusted services, to ensure a high level of security and reliability. By aligning with the technical architecture of the EU Digital Identity Wallet ARF, the solution delivers secure, reusable, and interoperable proofs of age.
> The solution enables users to present their Proof of Age attestation to Relying Parties, primarily for online use cases. The system is optimised for secure and privacy-preserving online presentation, allowing users to prove their eligibility without disclosing unnecessary personal information.
— https://github.com/eu-digital-identity-wallet/av-doc-technic...
Annex A includes details on the ZKP:
> AVI SHOULD support the generation of Zero-Knowledge Proofs using the solution detailed in: "Matteo Frigo and abhi shelat, Anonymous credentials from ECDSA, Cryptology ePrint Archive, Paper 2024/2010, 2024, available at https://eprint.iacr.org/2024/2010".
— https://github.com/eu-digital-identity-wallet/av-doc-technic...
And the linked paper:
> Anonymous digital credentials allow a user to prove possession of an attribute that has been asserted by an identity issuer without revealing any extra information about themselves. For example, a user who has received a digital passport credential can prove their “age is ” without revealing any other attributes such as their name or date of birth.