Logically, any service, whether private or not, is required by law to reveal the user data they have, if there is a court order for a criminal investigation. Proton cannot refuse, if it does not want to face a complaint that could even lead to the closure of its service. That is, in this headline the “Proton Mail” can be replaced by any other email, host, chat, social network, VPN, Lemmy, it can occur in any of them. As said, read TOS and PP of what you use