Can a website tell if my location is faked?
Not from the location itself. A browser gives a website a latitude, a longitude and an accuracy radius, and nothing in them says whether the position was real or set by a mock location app. What a website can still see is your internet connection, and the city it points to.
What a website receives
When you allow location, the browser passes on the latitude, the longitude and an accuracy in meters, and sometimes altitude with its own accuracy, heading and speed. MDN’s reference lists those fields and nothing more: no field marks a position as simulated.
How a phone fakes its position
Android’s Developer options include “Select mock location app”, which Google describes as a way to fake the GPS location of the device to test how an app behaves in other places. The phone then hands the fake point to anything that asks for its location, the browser included. It is a testing tool, and the accuracy radius that comes with the fake point is whatever the app sets.
What a fake position does not change
Your IP address still belongs to your internet provider, mobile carrier or VPN, and location databases still map it to an approximate city. The device’s own time-zone setting stays as it was. A faked point far from both is the kind of mismatch a site can notice.
See what a site can compare
The IP location page here shows the city your connection points to, and the time-zone page compares your device’s clock setting with the zone at the point you choose. If your real position looks wrong rather than faked, the guide to turning location on and fixing it is the place to start.