Samsung
Turn Adaptive Brightness On or Off auf Samsung
Adaptive brightness uses the light sensor on your Samsung phone to raise or lower screen brightness automatically as lighting conditions change. Once enabled, it learns from every manual adjustment you make and applies similar changes the next time it detects comparable light levels.
This is why the screen sometimes looks too dim in a bright room or too bright at night, even after you drag the brightness slider yourself. The feature is trying to predict your preference rather than following a fixed value.
Where to find the setting
Go to Settings ➔ Display ➔ Adaptive brightness to enable or disable it. Turning it off gives you full manual control over the brightness slider, with no automatic changes based on the light sensor.
Turning it on is useful if you move between very different lighting environments often, since the phone adjusts for you instead of requiring constant manual tweaks. Turning it off makes more sense if you want a consistent brightness level regardless of surroundings, or if you noticed the screen behaving inconsistently after software updates.
If brightness still feels wrong after disabling the feature, check whether battery saving modes are limiting maximum brightness separately, since that setting works independently from Adaptive brightness.