Default color space and HDMI RGB range

[ActionA]

Vero 4K H265 movies (8-bit encoded only?) - blacks show as grey, colours washed out (reduced colourspace)

Confirming you are using NOT configuring any of these displays for RGB only HDMI input ? AMLogic devices use a YCbCr color space by default.

This was at the top of the list when using the forum search for “default color space”.