Tempmail.com and temp-mail.org are blocking tor users. Tested some other random service that works, but proton blocked their mail domains
You can’t create proton account anonymously very easily. If attempting to create account using for, you’re prompted to enter phone number or existing email iirc.
Edit: just tested, existing email is needed. This already tells they do not want people to create accounts in a privacy respecting way even if it’s somewhat trivial to bypass if you know how
Goddamnit