This is misleading. They are merely exploring options that may allow for issuer unlinkability, but they are actually implementing a linkable solution based on standard cryptography that allows issuers (member state governments) to collude with any verifier (a website requiring age verification) to de-anonymize users. The solution is linkable because both the issuer and the verifier see the same identifiers (the SD-JWT and its signature).
The project is supposed to prove that age verification is viable so that the Commission can use it as a success story, while it completely disregards privacy by design principles in its implementation. That the project intends to perhaps at some point implement privacy enhancing technologies doesn't make it any better. Nothing is more permanent than a temporary solution.
It will also be trivial to circumvent [1], potentially leading to a cycle of obfuscation and weakening of privacy features that are present in the current issuer linkable design.