A fade is a purposeful deficiency... for reasons i cannot fathom, but that is exactly what it is, in any case.
changing colors can be inevitable. Senescence will occur even if feeding properly until the end. some plants exhibit it differently than others.
your plants look a bit overfed outside of the purple, so i'd chalk this up to senescence. It'll be a while before the plant sucks those overly lush and "clawing" leaves down. they have a tone of nutes in them, which is not going to impact resulting flower. Nutrient content of leves is different because it functions as astorage facility, which flowers do not.. they are sex organs and their function has nothing to do with storing excess minerals. the cells will be constructed as the dna instructs.
if oyu eat a bunch of tacos, do your muscles turn to taco meat? no, because that would be absurd and not how 'biology' works. You may pack on some extra adipose tissue, but it doesn't change the physical contituents of your bones or hair etc... your balls or ovaries will not be flooded with fat or taco meat... which is basically what people are saying when they repeat the nonsense that mineral context of flower is somehow impacted by fertilization the last 2 weeks of life... it isn't. proven false. not a grey area in which a mistake could be made.