Proton are very transparent about what data is and isn’t stored, how data is protected and what (very limited) data may be available in the event of a legal warrant - going through all the proper channels.

Complying with legal warrants doesnt make the service insecure or not private. It makes it a legal and legitimate company.

It shouldn’t really be a surprise to any of it’s users.

From the article (emphasis is mine): Is Proton Mail still secure and private? … In short, the answer is yes if you are looking for a secure, encrypted email service that does not have access to the contents of your inbox. After all, ProtonMail is far better than Gmail or Yahoo when it comes to privacy.

If you are doing things to attract the attention of law enforcement, then the data you provide when you use ProtonMail, such as IP address and recovery email, may be shared with authorities if Proton Technologies is legally compelled to do so in Swiss court.