If you need port forwarding for qBittorrent + Arr + Gluetun, Mullvad isn’t an option anymore. They removed port forwarding in 2023.

That basically leaves Proton or AirVPN. Proton still supports port forwarding on P2P servers, while AirVPN is the more “power-user” option with persistent forwarded ports.

So if port forwarding matters for your setup, dropping Proton for Mullvad would actually break the functionality you’re using.