If I understood correctly from Proton’s privacy policy, VPN does not log IP addresses but at least in some circumstances Mail does. This is from their privacy policy:

Due to limitations of the SMTP protocol, we have access to the following email metadata: sender and recipient email addresses, the IP address incoming messages originated from, attachment name, message subject, and message sent and received times.

One thing must be remembered: Even Proton must follow the law and rules.