You can try switching to a different HDMI port to see if that resolves the issue ... and go to Screen and Video > Video ...
But if you’re watching ‘normal’ 4K HDR video, any old HDMI cable should do. The full-size 19-pin Type-A HDMI port is the one you’ll see on the back of your TV and things like Blu-ray players and game ...
At a minimum, eARC requires that both an audio device and its connected HDMI port support HDMI 2.1. If you're unsure, check your audio gear's specifications, and connect it to the port marked ...
If you want an easy way to connect your laptop, phone, or tablet to your TV or an external monitor, this Anker USB-C-to-HDMI adapter is a great solution, especially now that it’s only $12 on Amazon.