Anyone notice their lower screen changing brightness on occasions?

Mine sometimes displays slightly more dull / less bright and I can’t figure out if it’s adapting to night time mode or perhaps I’ve got a bug.

The upper screen changes completely to a night time mode with inverse dark colours but the lower screen stays the same colours.

I can’t work it out. MY19 5.0SC Dynamic AB - Boss Grey, Black Pano Roof, 22” Gloss Black Alloys, Ebony/Ivory Massage Seats, Carbon Fibre Finishers, HUD, DTV and the all important Cabin Ionisation...