>a whois on my public IP revealed that it belongs to the original ISP, not whatever local ISP I was using
did you do other checks to see if your traffic was being censored? a whois of your public ip says nothing about whether your traffic has been manipulated.
> Even visiting Google shows the Google page of the original country. I guess they just have agreements to tunnel traffic in a way that circumvents the Great Firewall.
The Great Firewall doesn't in general modify traffic. It either allows traffic to pass though, or blocks it (TCP RST, rate limiting, etc). I was able to visit normally blocked sites like Google at full speed of a typical cellular connection.
did you do other checks to see if your traffic was being censored? a whois of your public ip says nothing about whether your traffic has been manipulated.
> Even visiting Google shows the Google page of the original country. I guess they just have agreements to tunnel traffic in a way that circumvents the Great Firewall.
google serves pages depending on your public ip