Is to test it on another one.
Here's a thing. Even today's TVs are not "picture perfect." These bands could be due to dynamic back light dimming, source issues and other.
Use your LG and seller support to see if they can sort it out. If not, return it for another set until you find a set you like.
Whenever I'm watching a show or movie, I can't help but see these faint fixed vertical (shadow-like) bands that are apparent with a moving light or white background. On darker backgrounds, you cant see them at all. Is this normal? Should I calibrate the picture to eliminate these bands?
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