Dear Samsung Member,
Greetings from Samsung Customer Support!
To resolve display "brightness" issue kindly follow the below step given below:-
1. Adjust brightness on auto mode:- Go to Settings > Display > Tap on Auto brightness > Toggle switch to Enable Auto brightness.
2. Reset the device:- Settings >General Management > Tap on Reset.
Note: Before reset make sure to have back up of the data via Smart Switch Mobile App
(Install Smart Switch App > Open > Click on Memory Card Icon >Back Up option > Choose the data for Back up > Back Up).
If the issue still persist, kindly register your concern in Samsung Members app (Samsung Members app > Get help > Feedback > Error report/ask question).
Note: Please send device log files within 15 minutes of issue occurrence along with the exact issue details.
Thank you for writing to Samsung.
Samsung Customer Support