With your info, I'm almost positive that the issue is the HDMI cable or the HDMI port for that TV. Try changing the HDMI cable and see if the issue persists. Don't worry about the cable, there is no such thing as a 4K HDMI cable, purchase one within your budget. Consider to search for a high speed speed HDMI cable and that should do the trick.
For you to confirm the whole thing about the HDMI, give this article a glance 🙂