Proton's VPN routes users through encrypted tunnels, and the VPN app for iOS supports advanced security features, such as Secure Core, which passes mobile user traffic through multiple servers (325 servers are available) to defend against bad actors attempting to trace mobile IP addresses, and Tor via VPN. The new app also uses the latest Internet Key Exchange (IKEv2) protocol, which provides for higher speeds and stability on a VPN network.
I'm always on the lookout for better VPN services. I started with Protonmail years ago when I was looking for a better way to email tax documents. I liked what Protonmail had to say about privacy. I really like what they are saying about VPN now. But who knows, I could be a sucker on two accounts.
I do think VPNs are a good thing but are too complicated for most of us to understand. There's a lot of trust (or ignorance) required to use them. I already don't trust my mobile carriers or ISPs so the question is who do I mistrust more. One advantage to a VPN in my real-world life is that a VPN can often get around network restrictions that prevent SFTP or SSH access. This is something I run into regularly when trying to manage a server while on a mobile device. VPNs somewhat hide that traffic and get around some network filters.