The problem shows up when you let the phone automaticly adjust brightnes of the screen, because after some time it wants to change the brightnes thise depends on the natural light, but it cant change brightnes because of some software isues (you can se litle bridgnes changes on screen or blinking). I noticed thise when i startet a app called sony diagnostic when i was testing the screen. The screen was trying to change brightnes so you could see a white screen chaning litle bit the white color and blinking black for few 1 miliseconds.
So to fix this problem just press the icon that is showed on the attached picture and the icon should color blue, this worked for me.
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