REFUSED TO REMOVE MY GMAIL account information after trying their ProtonMail application. After being happy as a VPN customer, i tried ProtonMail. I stupidly allowed them to access my Gmail account, then when I was unhappy with the product, I could not get their service to remove my Gmail account, and it continued accessing my account. I was forced to use Google to remove their access because their support organization would not help me. Then, I demanded they close my account and remove my personal data under the Federal Act on Data Protection (FADP) in Switzerland. They have refused thus far with no response. They have thus far still not removed my account.
Recently migrated to ProtonVPN from another VPN provider. Using manual OpenVpn setup 2.6.x with DCO. Good service but... ProtonVPN does not allow data cipher AES-128-GCM, only AES-256-GCM. The former cipher is faster, and just as secure as the latter cipher. Using AES-128-GCM for my TLS cipher but would also like it for my data cipher. Would help speed improvements.
I have used many VPNs but ProtonVPN is more convenient because of its transparency. Support, Valuing the Community, Answering Questions is what makes me trust them. For the technical side, I haven't found any problems. I tested many servers, all using DNSSec. The Stealth invisibility feature is very useful I have tried it in one of the countries I visited (some providers block vpn networks).