proton-vpn-gtk-app is the official Proton VPN app repackaged by upstream Arch LInux.
It is unsupported by Proton VPN on Arch Linux - because of the repackage - but otherwise it work as expected.
We currently don’t support installation of our official app through Flatpak or the [Arch official extra repositories(Arch Linux - proton-vpn-gtk-app 4.8.2-1 (any)), although community contributors have published unofficial versions that you can use at your own risk. These may work, but they are not developed by us and we can’t provide support for them.
– How to use Proton VPN on Linux | Proton VPN
I have taken precautionary steps to ensure compatibility by switching my system to use systemd-resolved as my DNS resolver.
Although the following is about NordVPN the underlying DNS issue is exactly the same.
→ [root tip] [How To] Make Manjaro compatible with major VPN providers
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