My cell phone is dimming while using it?

@akrammokdad if your phone is dimming while you're right in the middle of using it, you're usually looking at things like the Adaptive Brightness errors or background power saving features interfering with your display driver.

First, rule out the light sensor by opening Settings==> Display and toggling Adaptive Brightness completely OFF.

If turning that off doesn't fix it check your software power toggles. Swipe down twice from the top of your screen to open your Quick Settings menu and make sure the Extra Dim isn't toggled on. You'll also want to go into Settings ==> Accessibility ==> Vision enhancements and make sure that Extra Dim is disabled. While you're in Settings, go to Battery, make sure that standard Power Saving is turned off, tap the top-right menu to disable Adaptive power saving, and go into Advanced features ==> Motions and Gestures to turn on Keep screen while viewing so the front camera tracks when you're looking at the display.

Let us know what you find out when you do these things. Ultimately a bad ambient light sensor can also be the issue. If so, I'd replace the Proximity Light Sensor Flex Cable and then re-evaluate. Let us know what you find out.