DIAGNOSIS: Smearing happens because you're rubbing oils and dust around. The anti-glare coating on these screens is delicate and can be damaged by cleaners or rough cloths.
FIX: 1) Power off the TV so you can see streaks. 2) Use a dry, clean, high-quality microfiber cloth designed for glasses or screens. 3) Gently wipe in one direction, preferably straight across, using very light pressure. Lift the cloth after each pass. For stubborn spots, lightly dampen a corner of the cloth with distilled water—just a few drops—and use that spot to gently clean the area, then immediately dry it with the dry part of the cloth.
IF THAT DIDN'T WORK: If you've already used a chemical cleaner and there's a hazy residue, you may have damaged the coating. Unfortunately, there's no safe way to 'strip' the damaged coating. You'll have to live with it or, if it's severe, pursue a warranty claim for screen damage.
HEADS UP: Never, ever spray anything directly onto the screen. The liquid can seep into the edges and damage the Mini-LED backlight array or the electronics behind the panel. Always spray onto the cloth, and even then, only use water or a screen cleaner specifically labeled as safe for coated displays.