tl;dr: The “zero knowledge” proof could have a finite number of uses per block of time for each verifier, each of which represented by a unique single-use key. This way anyone sharing keys would be limited by that finite number of uses, and if people sharing this aren’t coordinated they could end up re-using a single-use key.

If the encryption was stolen without their consent, this could tip a user off prompting them to invalidate the current set and get a new one. And if the verification is used to support a pseudonym like an account for an online service then instances of re-use could get flagged for moderators.