How can a site bypass VPN without using geolocation?

(I was instructed to repost if related questions didn’t answer my question. I’ll try to explain my question better.)

There’s a website and it shows two pieces of information when you chat with another user.

“IP location” and “Detected location”.

When I used a VPN (and WebRTC off), the “IP location” changed to the VPN location, but the “Detected location” remained the real location! So the site was able to bypass VPN.

Does anyone understand how this is possible?

I tried several other sites but not a single one was able to detect real location. Sites like only saw the VPN location. So I know the VPN is solid. Some sites use geolocation (e.g., but for that, the browser shows notification asking for permission. But in the case of this site, the browser didn’t give any location indication.

In related questions, there’s discussion about Google Maps, but on fresh browser even can’t bypass the VPN (and shows the VPN location). Then if you click on the small circle, browser will ask to allow location permission. So unless you allow GM can’t get your location.

So I’m curious to understand how is this possible?