VPNs leak and can be tricky to manage. I believe most serious torrent pirates use seedboxes at this point.
Mullvad and I’m sure other modern VPN clients have “kill switches” built-in that shuts down traffic if the tunnel isn’t on. You can also do a leak check before starting anything up.
Having wrote that, another option, under Linux with network namespaces and Wireguard it's possible to have a pretty fail proof VPN...