LMAO, it’s a difficult question. If a VPN doesn’t have IP leaks, the opened sites can see fake IP ONLY. It’s a different matter how they view such fake. The thing is that it’s possible to guess whether an IP address belongs to the ISP, catering the users, or to the data center. If it belongs to the data center, it’s highly likely we deal with VPN or proxy. However, we cannot trust this information 100% and trustworthy sites won’t give consideration to this information only. IP addresses can migrate, databases aren’t 100% accurate, etc. That’s why in “paranodes” cases sites can check your local time with the time zone of IP address. One can prevent it by changing the time on the device manually. Your real IP address will not be detected. As for your internet provider, it cannot decode a VPN channel. It cannot show your IP address to the sites you visit because it doesn’t know what sites you open.