Not all VPN traffic. Only traffic that would be routable without a VPN.

This works by tricking the computer into routing traffic to the attacker’s gateway instead of the VPN’s gateway. It doesn’t give the attacker access to the VPN gateway.

So traffic intended for a private network that is only accessible via VPN (like if you were connecting to a corporate network for example) wouldn’t be compromised. You simply wouldn’t be able to connect through the attacker’s gateway to the private network, and there wouldn’t be traffic to intercept.

This attack doesn’t break TLS encryption either. Anything you access over https (which is the vast majority of the internet these days) would still be just as encrypted as if you weren’t using a VPN.

For most people, in most scenarios, this amount to a small invasion of privacy. Our hypothetical malicious coffee shop could tell the ip addresses of websites you’re visiting, but probably not what you’re doing on those websites, unless it was an insecure website to begin with. Which is the case with or with VPN.

For some people or some situations that is a MASSIVE concern. People who use VPNs to hide what they’re doing from state level actors come to mind.

But for the average person who’s just using a VPN because they’re privacy conscious, or because they’re location spoofing. This is not going to represent a significant risk.