This specific problem is solved by requiring that any anonymous ZK ID once used for an account be marked on an immutable ledger preventing multiple uses of the same ID. Sharing it would be pointless as multiple attempts to use it get burned. Yet none of those sites know who you are, only that you have a unique valid ID pass. They just have to check any login attempts against that ledger - easy enough.

> They just have to check any login attempts against that ledger - easy enough.

So like CT logs, but several orders of magnitude bigger? I thought centralized TLS revocation lists failed due to scale. How will this differ?