I tested the same dream and I saw some imperfection on my system, wonder it is the same as yours. What I saw is the same thing appear on Mike (Azdude) Preview video. Are you seeing the same things? There are jagged edge or pixelated. Perhaps, this is how it suppose to be or my setting is off too. Hopefully Mike can come in and confirm it.
I believe, the video itself is at 4K just that when the compression is done to make the dream file smaller in size, perhaps some details are lost.
Mike's Preview video.
Thank you,
Basj,
Stardock Community Assistant