WHAT IF red devils have a maturity colouration. they deepen or fade in colour to show maturity. i have zero idea if this is true but its a blind guess. either way... if it IS true, the gene that tells the red devil to mature in colour at a certain age is telling the colouration to turn red and its destroying the flowerhorn colouring. like a black horse foal turning white when it grows up, cos that's the genetics.
that, or the colours are just messing up with the random genes it has. there is my conclusion