Thank you for your response.
Actually, GND_system and GND_internal are different, Because there is a MOSFET (reverse polarity protection) between them. That makes sense. But why have they separated GND_internal and GND_shifted? below 12v they are tied together; between 12 up to 30, they are connected by a PNP transistor, and more than 30V, they are connected via a diode (cathode connected to GND_shifted and Anode to GND_internal). according to the switch driver and no control GND drift, seems it is ok without this ground separation. I cannot understand yet!