Your phone can provide precise location information by using GPS satellites. It also can report the names of nearby wi-fi hotspots. Possibly cell towers could be used. If those were being used, you should not be getting this behavior. The most general method a site can use is your IP address, which is linked to a particular service provider. To see where sites think your IP address is, try this page: https://www.iplocation.net/ Note: if you use a VPN, your IP address is determined by the VPN and not your own service provider.