Why is custard powder pink until you add the liquid, upon which it becomes yellow?

Custard powder is often coloured with a blend of tartrazine yellow or quinoline yellow food dyes, mixed with sunset yellow. In solution with water, these colours are true to their names, but in their pre-dissolved solid phase the sunset yellow portion is more orange-red, and this colour tends to dominate.

When mixed with the other custard powder components, which are white, the result is a pastel orange-red, or pink. Many pure colourants, both dyes and pigments, have a very different shade from that required in their final state.

https://www.newscientist.com/lastword/mg19526191-600-colour-of-custard/