I always think of the diff height as an influencer of on-power and braking fore/aft weight transfer, although there may be other explanations as to its effect. My reasoning to this is that the moments about the car's CG due to the belt tensions during power and braking effect the cars attitude, or at least its fore/aft weight transfer. Nevertheless, to me the changes are hard to notice on the track, at least in blinky 17.5.

Raise the front diff height: more on-power rear weight xfer (i.e. more squat), less dive under braking.

Lower the front diff height: opposite of above.

Raise the rear diff height: less rear squat on-power, more dive under braking.

Lower the rear diff height: opposite of above.