With MacBook Airs, this is always an issue with the LCD itself, not the LCD cable. Basically, one of the 2 ribbons going from the display itself to the screen PCB goes bad, causing either a white fading screen, grey screen with even vertical lines, or distorted bars to run down the screen. The only way to resolve this issue is to replace the screen, or the whole top lid assembly.
Usually this happens with the LG panels, rarely it can happen with the Samsung panels. If you were willing to attempt the job, check out this video and remove the silver bezel https://www.youtube.com/watch?v=O3lhuy3s.... After doing this, you can push on the ribbon and usually the picture will cut in and out, unless it has completely failed.
After repairing over 1000 MacBook Air screens, a lot of which develop issues like you are describing for no reason, I have never seen one with a failed cable. I have only replaced LCD cables on Airs and Retinas if they are physically damaged from liquid, I have never had to replace them due to picture issues (they are a lot more reliable than the older 2009-2010 MacBook Pro LCD cable issues.