If you pop open Digital Color Meter app (macOS system util), are there any differences between the whites in the video and the #fff interface whites?
> The operating system is complicit in this trickery, so the Digital Color Meter eyedropper shows “white” as 255, as do screenshots.
I wonder if other measurement tools (e.g. Adobe color picker) are also fooled by the OS in this case.
Digital Color Meter shows both UI white and video white as exactly #fff despite the video white being much brighter!
Even at full screen brightness, the video white was noticeably brighter