tun0 goes away when I am disconnected, so I don’t think anything is keeping it open. I noticed that connections in Proton VPN were set to UDP, so I changed this to TCP and this seems to have worked. Will still want to do more testing to be sure.
I don’t seem to have v3 installed, by the way. The old GUI tool seems to have been uninstalled when upgrading, and the CLI tool I unisntalled myself.