The same colour can look genuinely different depending on room orientation, time of day and bulb type — never presented here as an exact physical prediction, only as what commonly changes and what to check for.
Colour in north-facing rooms
What colour works well in a north-facing room?
Colour in south-facing rooms
What colour works well in a south-facing room?
Colour in east- and west-facing rooms
How does morning and evening light affect a room's colour?
Colour in rooms with low natural light
What colours work well in a room with little natural light?
Warm vs cool artificial light
Why does paint look different at night, or under different bulbs?
Colour temperature and CRI, explained
What is colour temperature and what is CRI?
Metamerism and why colours look different beside other colours
What is metamerism, and why do colours look different next to other colours?
Why paint changes from sample to wall, and why screens look different
Why does paint look different on the wall than on the sample, or on a screen?
Morning light, evening light and the hours between
Why does a colour look different in the morning and the evening?
How a colour changes the colour next to it
Why does a colour look different depending on what is beside it?