Thought I would chip in with my experience with LG and burn-in. You can see how bad mine is, below. This is a B7 at 2 years old. Raised to LG around 1 and a half years after buying.
There are 4 separate instances of burn in, not including the blob in the middle. The 4 logos are Nickelodeon (bottom right), Good morning Britain (bottom left), You Tube from my NVIDIA Shield home screen (top left). Each should take thousands of hours to achieve this level of burn in, apparently. Which I can assure you has not been the case.
LG's response to this has made me angry. You can clearly see this is bad. All we have done is watch TV on the unit, which if I'm not mistaken is it's primary task. We have been told "electronics break" and we have not been using the TV correctly, like this was my fault!! They want £200 to fix it, which is a damn cheek. I complained to Richer Sounds about the experience and they have kindly said they would pay the £200 cost. They also said this is really common on LG sets they sell.
Now, LG aren't repairing TV's due to COVID and we're stuck watching grey faces all the time. Yayy!! [/sarcasim]
Safe to say, this is my last time buying LG, which is a shame as the TV is brilliant when it works.