+1 to solve this.
We are using this variable in several MSFS 2020 planes to change the brightness of some displays (e.g. HUD in “AUTO” brightness mode)… and this does not work as expected in 2024.
Thanks - good tip, although we have a big number of displays and changing all of them to use that variable may not be practical… but maybe worth trying in any case if this does not get fixed quickly…