Out of sheer curiosity, is there any rules against a justice to secretly record audio of what the other justices are saying behind closed doors and leaking it to the press? In other words, if we crumble to a dictatorship, what would ketanji say she wished she had done besides a strong dessent?

Is DC a two-party consent to recording “state”?

They aren't bound by any sort of ethics rules, so... no.