Before 7.0(i.e., 6.8 or 6.9) i have to put brightness at 30% atleast to be able to see the screen otherwise it is too dark to see the screen even during night time but now the issue is resolved(i put 0 to 2 % and i can see easily as on moto g32 stock Android )
I put a headphone and reboot the device, it soft-reboot into bootloop over and over again but now it doesnot give anymore bootloop problems
Note: this post is different from the one you pointed out and which i posted. This one is related to brightness issue and bootloop and the other about *auto-brightness functioning in sunlight* even when auto-brightness feature is off