How’s your monitor/screen calibration? Look at this image and observe the gradations between black and white in the diagrams. You should be able to see the subtle difference between A/B/C and X/Y/Z brightnesses in the chart.
If you can’t see the difference between the dark patches A, B, and C, then your screen’s calibration is shifted too far to the dark side and you won’t be able to see details in photos with deep shadows or overall dark appearance.
If you can’t see the difference between the light patches X, Y, and Z, then your screen’s calibration is shifted too far to the light side and you won’t be able to see details or faint colors in overall bright photos or graphics.
This is not related to what brightness level you have set on your phone or monitor, but concerns your screen’s ability to display or distinguish between very dark or very white image tones.
Most modern mobile phones have very good screens and should perform well. Desktop/laptop screen can often be adjusted; look to see if yours has any such adjustments.