Went to Apple Store yesterday due to remote skipping tiles when pressing down button on clickpad. Genius bar didn’t bother to look at remote and just ordered a replacement. Like you, I tried to diagnose and resolve first but it’s better to just go and have Apple give you a new one. They can fix the remote themselves if they want to.

On all my 4K AppleTVs, YouTube doesn’t like Dynamic Range matching. It allows Frame Rate though, so I disable Range matching when using YouTube.