If you pay Proton Mail for a service, they may hand over the payment data in response to a court order: https://www.404media.co/proton-mail-helped-fbi-unmask-anonymous-stop-cop-city-protestor/
Proton Mail Helped FBI Unmask Anonymous ‘Stop Cop City’ Protester

A court record reviewed by 404 Media shows privacy-focused email provider Proton Mail handed over payment data related to a Stop Cop City email account to the Swiss government, which handed it to the FBI.

404 Media

@evacide

The only winning move is not to pay.

Not quite as privacy focued as they claim really.

@simonzerafa @evacide  I think you mean "anonymity" rather than "privacy". No corporation is immune to legal compulsion. If you link a credit card to an account of any type, it will show up in all kinds of metadata via credit card companies and data brokers, and the banking records will forever deanonymize the account.

So yes, pay for a ProtonMail account with CC if you want, but use a free one if you want *anonymity* in addition to privacy.