The GPS data message containing the time the message was transmitted and the location of the transmitter at that time could of course be faked. However what can not be faked is the time it takes to arrive at a receiver. All receivers equally distant from the actual transmitter location will acquire the same message at the same time. But they compute the distance based on the claimed transmitter location in the data message. If the actual and claimed locations of the transmitters are not the same GPS will not work. But it does work, so they are the same. Ergo the transmitters are in orbit so the earth can be orbited so its round.
There are so many aspects of the reality of day to day life that is actively ignored by flat earth believers that disproves their beliefs.
This is why they avoid thinking about them. They pretend they are free thinkers when in reality they are non thinkers.
To counter reality they have to make up silly blatant lies. Lies such as telescopes are being hidden from the general public preventing them from seeing the truth about the cosmos!
The irony is the actual truth is there for anyone with some free cash to see for themselves. Its just a demonstration of how flat earth belief is built on a foundation of easily disproven lies.
https://shop.uk.unistellar.com/products/odyssey?variant=48154348061007It’s ironic when flat earthers are banging away on a keyboard saying how space travel and satellites are all a fiction while at the same time their message is being routed by some geostationary satellite!
Such is the blindness and madness of the flat earth believer.