TCL TV sometimes just dark?

Pi
2

I bought a TCL 4k TV a few months ago. When I switch to Netflix or the Apple TV, the screen is only half as bright, so very dark. I can restart the TV so that it is bright again, but would still like to know what kind of dirt it is?!

Av

Reset it once to the factory setting, a password is requested, then enter 0423

Pi

Ok let's see if it continues to happen