It may have happened in 2021 but apparently it seems
Proton handed over email related information including IP addresses to French authorities that requested them via a Swiss court. When that request arrived, the Swiss judge forced Proton to log and disclose the IP and browser fingerprint of a specific person. That basically is shocking even though they provided mitigation by saying they had no choice as it was a legal request they had to comply with. All that because the French authorities were seeking information on a
climate activist.
This is more of a problem with France than with Proton. Just yesterday, they also arrested the Telegram founder Pavel Durov for not giving them the encryption keys to decrypt all of their user's messages.
I think the issue about the climate activist was down to a Swiss court forcing Proton to adhere to the ruling/request. They did state later that the French authorities would never have been able to identify/locate the climate activist if he had used a VPN as they would have handed over the VPN IP address rather than the IP address of the mobile phone the climate activist was using at the time. Still, they published one piece of information about their no-logging policy but breached it and removed it entirely from their website after the backlash.
And you know what would happen once one government gets a hold of the decryption keys, they share them with all the other governments upon request.
If he had access to the decryption keys at the time of the arrest in France then many Telegram users will certainly be worried but I doubt he would carry them with him. It seems the problem France have against Durov is the lack of moderation on Telegram. If that is the case they have against him then owners/operators and shareholders of Microsoft, Meta, Google and many others should have been arrested when they stepped foot in France too because platforms they provide are hardly moderated.
There is a difference between a platform being hardly moderated and the police / government showing up and saying your platform is being used for a crime here is the what we have about when and where and how the crime is being committed and all you have to do is show us who.
If ask to borrow your car and you say yes and then I use it to rob a bank you are probably not going to be charged with anything.
If the cops show up BEFORE I ASK and tell you that I rob banks and borrow peoples cars to do it and they found out I am going to rob a bank later today and you still loan me your car then yeah, they are coming after you too.
-Dave