Display changing brightness randomly

hi,

turned off auto brightness and auto white balance in display accommodations. Still having on true tone. But my display still jumps in brightness randomly, means it doesn’t stay very bright. And after some time it goes back to 100%

some debugging to find incoaistencies.

turning on auto brightness, then turning off immediately and raising brightness back to normal will only result in brightness change until 50-60% upper half will not change a thing.

secondly, while changing brightness at around 25% the colors of brightness, volume and do not disturb buttons invert partially as if it’s some open gl glitch.

Ios 11.2.6 a iphone x while being plugged in.