I’ve noticed this a long time ago but didn’t really care much because it didn’t really bother me.
Usually I would put my screen brightness to max when I am going to takeoff/land from an airport that is at night. I notice that the brightness would sometimes suddenly dim. I cannot increase the brightness from the settings because it’s already at 100%. It has been happening since February.
iOS 11.4 (I think)
Latest IF version (CRJ-1000 update)