(Sony KD-49X8005C, EU) Screen brightness, color and bright spot issue

Hello everyone!

I have a Sony KD-49X805C type 4K LED TV and I noticed that its brightness has recently decreased as well as appearing behind it behind the screen, the LEDs on the lighting and there are visibly brighter spots on the TV in some places.

I think this may be due to slippage / failure of the light-distributing "reflector" film.

Have you ever met one like this? Which is more likely that the motherboard and one of its components may be faulty or the screen panel may have failed?

Thank you for your help!