@mohanad Ibrahim
From what I can see so far, the cause is that the Vestel manufactured LED backlight strips turn blue after some time, and can then fail completely. These are what produces the white brightness behind the coloured pixel leds.
These were supplied to MANY TV manufacturers for a time, so many brands and models may get this.
If you are from the UK, you might be able to claim on the Consumer Rights Act 2015 (the item must be fit for purpose for 6 years).
See: https://www.ifixit.com/Answers/View/445366/Why+does+everything+have+a+blue+tint for background.
See this site for replacements, but be warned, the TV will need a very complex strip-down to get at the screen internal "guts" where these bars are that will need replacing (see the Youtube video - you will need some good expertise and care to do it). The parts are around £65, more for genuine LG, so could easily be £150 - £250 plus for an TV tech to do it.
BARS:
https://tvledbars.com/?s=43uj630v-ta&post_type=product
TYPICAL HOW-TO:
https://www.youtube.com/watch?v=h5Zyqowl6zg