I have seen 256 kW in my own car (Fremont built '23 MY RWD with 2170 cells). There are no V4 chargers, only V4 dispensers. All V4s that are installed today are connected to V3 cabinets (the actual charger).
It's likely 170 kW coming out of the charger and 163 kW going into the battery because there are losses.
The number we see on the display is total power from the charger to the car.
So thats the sum of charging power + battery heat + cabin heating /cooling and the power needed to keep the car awake.
I have several logs (scan my tesla to teslalogger) that shows the battery power, and the battery heating and total power that mathces the display. Display showing north of 260kW means around -250kW battery power or slightly more.