This is a 'fun' issue I spotted whilst watching a film last night.
This video shows a short excerpt from the film Searching (2018).. at about 52min:30sec. The FALD (Full Array Local Dimming) backlight system seems to have real trouble working out what to do with the satnav background which should be a solid/uniform colour.. but the light blue roads cause it a lot of problems.
This looks to me to show a disadvantage of FALD over edge-lit or OLED. At least that's the way it seems. I'm not entirely sure whether you could even solve this in software.
I have noticed similar blotches in menu systems of set-top boxes where most of the background is dark, but there's a strip of brightness/colour across the screen.
During 95% of 'regular' TV viewing it isn't a problem.. but this shows that FALD has its issues in certain situations.
I spotted this issue too while playing videogames :
See how the gauge on the bottom left is sometimes surrounded by an halo, sometimes by pitch black, due to the proximity to other background elements or not.
This FALD thing is a joke. In a game it's okayish but in a movie? How can you concentrate on the picture if you see the local dimming array tripping over its own feet.
I would gladly disable it and have grayer, more uniform blacks, anyday.