Seeing the leaked pictures of the significantly beefed up cooling, it must be for sensor/processor cooling and news of the rumoured jump in internal storage must point to the Mavic 4 Pro shooting at least 6K (and 24MP stills).
The extra stop on the lenses should then make up for the extra resolution and we hopefully get the improved processing and more modern sensor design tech from the Air 3S giving gains in dynamic range making this drone potentially very a tasty upgrade.
Would be surprised if they did BSI or even stacked sensors.
But we'll see.
The thing is Micro 4/3 sensors seem stuck at 20 Mp. Olympus just introduced a new camera the other week and it's a 20 Mp Micro 4/3 stacked sensor.