Chosen Solution
Has anyone seen an iPhone 11 Pro display that is very dimmed? It has around 1/3 brightness compared to my own iphone 11 pro max when I set brightness on highest. I reset the user settings to be sure it wasn’t a setting. The disply is already dimmed when you see the apple logo when booting. the phone was dropped and I replaced the backcover and cameralens on it. When I put another refurbished i11 pro display on it the brightness is fine. Have not seen this before on an iphone OLED. Faulty screen after drop I think but asking to be sure if anyone has experience with this.
Since you already troubleshooted with another device, the problem clearly seems to be in the screen or in the components attached to the screen. Brightness is controlled by the ambient light sensor in the screen, it could be that this sensor is damaged and it’s sensing “darkness” so it would dim the brightness of the screen backlight to not blind you while being in the dark. If you’re up to it you can try to swap those two parts of the screens you have and see if that fixes the problem. Have a look at step 26 of the iPhone 11 Pro screen repair. Note that this will require you to swap out the whole speaker & sensor assembly of the screens.
