It's the backlights. The emissions have fallen causing the colour change.
Swapping out the backlights should cure the problem, but you should also make some checks on the TV settings. If you're running with the contrast settings high - which would be the default if they haven't been changed - then this shortens the life of the backlights.
I'm sorry to be the bearer of bad news, but there's something you should know about LG TVs. At the higher-end, LG makes some superb TVs. It's OLED products are great. For the lower ranges though it's a different story. The closer you get to their entry-level product the greater the number of shortcuts taken. LGs tend to offer more features for the same price compared to Samsung, Sony and Panasonic, but to do that they economise in other areas. One place where this cost-cutting has become apparent is the backlighting.
LG uses fewer LEDs, and as a result it drives those LEDs harder. The result is that they burn though their life faster. Once they start to go then you get these colour shifts.
Another consequence of the LED issue is that base-level and some of the Nano-series TVs aren't as bright as the competition. The sets aren't as good for brightly-illuminated areas such as conservatories or rooms with a lot of natural light. The other issue relating to this is 4K HDR. This needs the set to produce more light output to give the HDR the extra pop it needs to show the additional brightness. Many LG sets have nothing left in reserve because the backlights are already working near flat out just for SDR.
Simply replacing the sets LED backlights may fix the immediate issue but still leave you with the longer-term problem. The TV's picture controls need to be adjusted - particularly the Contrast setting which is what governs the maximum brightness of the LEDs. Having the set running near flat out all the time will just cause the new LEDs to die just as quickly.
To set the TV correctly requires using some test patterns to be able to see what the TV does with a reference image. You can't do this as a novice by just looking at TV programmes and films. It's very likely that ordinary TV images have been Colour Graded (adjusted for brightness and contrast)
scene-by-scene to make the best use of the dynamic range range on offer. IOW, if you use a TV prog to set brightness and contrast with one scene, then it will be wrong for the next scene if it's substantially brighter or darker, so you end up riding the TV controls to compensate all the time. With test patterns you set up to the industry standard. This is the same standard the Grader used. That means you see what you should see in all scenes within the limits of the TV's performance.
The patterns you need are Brightness
Contrast
Mixed APL (Brightness and Contrast in the same image)
Sharpness
and... depending on whether you want to go the last mile - Colour
The above patterns are from the AVS HD 709 test pattern set which can be downloaded and used for free.
https://www.avsforum.com/threads/avs-hd-709-blu-ray-mp4-calibration.948496/
There's also a pdf user manual from which the above screen shots were grabbed. You're only reading the first two pages because the adjustments being done are very basic. Once you have an idea of what you're looking for then the total time to do the 4 or 5 settings is under 10 minutes. Yes, that's all it's going to take to get any TV running correctly for SDR.
The patterns can be downloaded and run from a USB stick in many TVs.
Glossary
SDR - Standard Dynamic Range - the difference between the darkest and brightest images that the TV can produce. SDR is what's used for normal TV broadcast including HD1080p. It's also what we have on DVD and Blu-ray.
HDR - High Dynamic Range - a system that attempts to replicate some of what we're used to seeing in life. With normal vision our eyes are able to see both shadow detail and highlight detail at the same time. An SDR-based system can't do this. That's why directors avoid shooting scenes with mixed lighting where important stuff is in both shadow and brightly-lit areas. They choose one or the other. With HDR there's far more scope for having both lowlight and highlight areas visible and correctly exposed at the same time; just like we see in life. To do this though requires that the TV be able to output extra light when playing HDR material (HDR10, HDR10+, DolbyVision, HLG) such as you might find on streaming sources from Amazon, DisneyPlus, premium Netflix and Apple TV.
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