Meanwhile, on Proton's homepage:

Highest standards of privacy

Proton is incorporated and headquartered in Switzerland, meaning your data is protected by some of the world's strictest privacy laws.

The standard for email privacy

From newsrooms, activists, and international organizations to academics, Nobel Prize winners, and movie characters, Proton Mail is the trusted choice for secure and private communication.

ultimately, it's the choice to use a credit card that created the issue. As Proton's statement mentions, it also accepts payment by cryptocurrency and cash, which could be better ways to keep your information private if you absolutely need to.