Traffic of onion-services is encrypted. Traffic correlation to deanonymize the client can still be theoretically performed but ultimately you need to draw the line in the sand somewhere.
> Regardless, protonmail doesn’t let people register when connecting with Tor unless you use phone number or card to make a payment
Actually if you attempt enough times you will get the option to verify the registration with an e-mail. And they are rather liberal with which options they accept. So it is not exactly a circular dependency.
From there is it an exercise to the reader to create an account not linked to any other identity.
