Low idle speed in Drive when press brake pedal

Hi Gents,

I am having a problem with a RAV4 2018 4WD, engine 2.5L, automatic gearbox.

The issue is with the idle speed when in Drive and press the brake pedal. In that circumstance the idle speed drops about 150 rpm , from 770 to 620 rpm aprox. ( it does not happen if the manual brake is applied )

I have cleaned the throttle body, have checked the brake booster for no leaks, vacuum lines, and the rear brake lights circuit ( presuming for a short circuit ), with no success.

It does not happen with headlights on or when the day/night sensor turns lights on or with A/C on, in other words the car compensates the extra charge from these consumers.
Only happens when lights are off and no other electrical consumers are on.

Any ideas? Programming issue? Is it normal? This is not something I cannot live with, but the car in these circumstances shakes a little bit.

Thanks for your help in advance