Privacy is not anonymity. In this case they were required to supply IP addresses of users logging into a certain account in an active investigation.

As usual, the devil is in the details—ProtonMail’s original policy simply said that the service does not keep IP logs “by default.” However, as a Swiss company itself, ProtonMail was obliged to comply with a Swiss court’s injunction demanding that it begin logging IP address and browser fingerprint information for a particular ProtonMail account.