VPNs log your IP. And Mullvad doesn't allow port-forwarding, which means you can't seed.
Being a node for traffic doesn't mean it can be linked to your identity, because everything is encrypted and metadata is scrambled. TOR node operators take much greater risks because depending on how they have set it up, it can lead to their identity being compromised. It's a small chance but it can happen.
I can't convince you. I only hope that people start seeing the need for it and begin reading the documentation to see its strengths
VPNs usually do store your IP when you connect to them, even if they delete it later (it is technically impossible to not know the IP address of whoever is connecting to the VPN). And the likes of Mullvad and IVPN do not allow port-forwarding.
I will repeat what I said to the other commenter: please read the documentation. Being a router doesn't mean that traffic and its contents can be linked to your identity. Data is broken down into chunks and encrypted along with metadata being scrambled. Unless there's a zero day I'm unaware of, you are perfectly safe.