since there hybrid. could be like those red devil/ white midas. how they fade etc... plus BP are breed from RD/ midas anyway. its normal. no dye. usually dyed are some funky color anyway which fade.
Easy way to detect dyed fish is to look along the lateral line. The pits along the line have a sensory function. These pits will pick up dye and will be darker or appear blotchy if dyed.