But if the VPN provider really was routing other customers traffic through your internet… you’d know it. You’d see requests and traffic that you didn’t make going across your router. Since you’d be the endpoint for the other dudes VPN you could probably even see what IPs they are connecting to and get an idea about the nature of their requests.

I dunno if SSL encrypts the entire HTTP payload or not but could you even figure out the URL’s being requested using a tool like wireshark?

Full URLs: Definitely not. Path and query parameters are part of the HTTP payload, i.e. encrypted within HTTPS.

Host names: Very likely, unless you're using SNI.

You mean eSNI, SNI is the field containing the hostname and eSNI stands for "encrypted SNI"

Right, thanks!

I keep thinking the "e" is for "enhanced" encryption, i.e. "eSNI 2.0", but what I'm thinking of is actually called ECH (for "encrypted client hello"): https://blog.cloudflare.com/encrypted-client-hello/

If such a feature exists (and I have no idea if it does) I assume they would only route traffic to known streaming services through it. Otherwise you're making random customers into exit nodes for potentially criminal traffic, which could go very badly.