Horizontal "scanlines" on aw2518HF

One day suddenly these scanlines appeared on my display (each strip being about 2 pixels tall), narrowed it down to being something on the display itself by trying different devices, inputs and cables.

Tried Factory Reset and LCD Conditioning and it's still there. On bright images or solid colors it's not as obvious, but it really screams on videos or games. Took a picture as an example, but the camera couldn't capture how bad it is.

Saw many similar posts but couldn't find a specific solution or any mention to what part or board causes the problem.

If anyone has information to share on this issue or the solution, it will be greatly appreciated.