Blurry image on LG 4K TV can be caused by various reasons. One of the reasons could be the picture mode setting. If the picture mode is set to Standard or Vivid, it can create more clarity and brightness, but it may also result in a blurry image. Another reason could be the resolution of the content being displayed. If the content is in lower resolution and is being displayed on a 4K TV which supports high-resolution images, the image may appear blurry or grainy. Additionally, using an older HDMI cable that is not high-speed or having a low bitrate setting can also result in a blurry image. To fix the issue, it is recommended to check the picture mode setting, use a device that supports 4K videos, use high-quality HDMI cables, set up 4K TV settings properly, and upscale the video to 4K resolution to fit the TV size. It is also advisable to change the sharpness settings and avoid sticking with default motion settings.