Just to be clear, you're not thinking there is anything wrong here, just asking why new leaves are generally a lighter brighter colour? See Why new leaves look lighter green Here's another: Why Are New Leaves a Lighter Color? - Bellevue Botanical Garden
Some plants produce red/brown new leaves with no chlorophyll at first - it has been suggested this is to fool herbivores into thinking that the tender new leaves they are looking at, are dead leaves not worth eating.