Bridged or teamed network cards are not an unusual or exotic configuration; you use them if you have more than one NIC in your PC and want to use them efficiently, and some virtual machine software (such as Fedora libvirt) require that VM guests use bridged network connections on the host if you want those VM guests to act as independent entities on the local network.
The current Proton VPN app and CLI fail to connect and actually bring down the PC's network on Linux Fedora (44) if that PC has a network bridge.
The current workaround is to download a Wireguard or OpenVPN configuration file provided at the Proton VPN website and load that into the network manager (https://protonvpn.com/support/wireguard-configurations). This works fine, but it would be better if the app and CLI worked properly too.
This bridging/teaming issue may affect Proton VPN on Windows or MacOS too, but I haven't tested these.