It’s very similar to live plants in freshwater that have an adjustment period, where they may look duller than normal for a few days to week and then they should brighten up. I would only be concerned if they start to loose all coloration (ex; turn grey/white) and don’t open up or accept any food when our near them when the lights are on.
When you bought it, did you look under it without the commonly found blue lights to enhance their color? I’ve bought a few and everytime they have those blue lights it can make it appear wildly different if you don’t have the same light spectrum they are shown under.