KDE and GNOME alike rely on the Mozilla Location Service (MLS) for their geolocation functionality.
The service takes a snapshot of the Wi-Fi signal information around the device and sends it to MLS, which in turns return an estimate of the device’s location. If you’ve used apps like GNOME Maps or even Firefox itself you may have realized that it’s not really all that accurate outside of big cities – or even in every neighborhood of the cities.