Protecting the interest of our customers and ensuring the stability of the service have been key principles for IVPN since starting our operations more than ten years ago. To keep delivering on these promises, we have made the decision to gradually phase out the port forwarding feature from the IVPN Pro plan.
The paid ProtonVPN has port-forwarding for its Windows app, not for Linux yet though.
If you download a wireguard/openVPN conf file from Proton it will let you enable nat-pmp which is basically automatic port forwarding. It seems to work fine on a Linux machine running qbittorrent, but your case might be different.