Normally, the MAC address of G2 4K will not change. May I ask what method you called to obtain it?
Also, what was done to cause the MAC address to change, so that we can reproduce the problem.
And could you please provide the version number of your PUI?
Moreover, you can find the MAC address of the device in the following location：
Settings->Developer->Network&Internet->Wi-Fi->Wi-Fi preferences->Advanced->MAC address