This is just ridiculous.. If they receive a notice to log your IP address, they should notify you first. My trust in ProtonMail is gone.
According to their statement: > Under Swiss law, it is obligatory for a user to be notified if a third party makes a request for their private data and such data is to be used in a criminal proceeding. But the timeline is unclear to me. If they notified you via e-mail, and then immediately turned on IP logging. So... you'd go and check your e-mail, learn about the third-party request, but by then it's too late as you…
If someone is so sensitive about leaking their IP address and they access some service with their real IP and relying on a service's promise to not log it they already are not very careful to begin with.