Hi my phone is samsung a70. For the last two weeks i am facing a weird problem. When i lock the phone, the top most portion of the screen flashes. Just for a second. Exactly when the lock sound is heard. That too in low brightness level. When it is high, i haven't noticed it. But there is no problem while using or unlocking or anything. Only when the device is locked. And when i lock after connecting the charger, the whole screen brights up and dims showing the charging information. That too in low brightness. This doesn't happen every time. Depends like a 3 or 4 out of 5 times
I have tried clearing cache partition and it didn't work. Also the lockscreen is brighter than homescreen even though face recognition is off. I have updated the device on may 3 2021 with april 1 security patch.
So what must be the problem ? Is it the software or the hardware? What can i do to fix this ?