It's this I believe: https://www.w3.org/TR/vc-data-model-2.0/

A Verifiable Credential fundamentally doesn't solve the problem of "sharing", "smuggling". All it takes is one verified adult to "leak" their VC somewhere, and millions of underage people would be able to use it to "prove" they are over 18.

This would only work with something like MS TPM 2 / Apple Secure Enclave (device attestation), which is anti-freedom by design. I was curious if they found a way around that (maybe with time/rate limits, or some actual useful use of blockchain tech).