Apple TV flickers on dark scenes.

I have an ATV4k 1st gen that flickers on dark scenes. Sometimes it's only on HD content, sometimes it's on HD and HDR (HDR10, DV) content. Depends on the OS.

Updates to the OS fix or break the flickering on HDR content. The last update added flickering to DV. Everything is connected properly. TV is set up correctly.

I've tried every single variation on the settings and nothing seems to work. PLEASE help.