Is this fade or nute def?

unless it finishes really fast, that's too early to strt fading unless very slow moving -- lots of plumping of calyxes remaining. all about rates of change and pictures are snapshots in time. that ff trio is always lacking something... your plants are some of the best i've seen using that trio of nutes, tbh. If the paling started at bottom and moved up, boost N a bit.. othwerise if located at top you might see an improvment if you reudce light intensity ever so slightly. 850ppfd? was tht using a phone app or a real quantum meter... either case.. a cuople more inches might reduce paling on the top leaves (if that's where it is starting to pale vs down below) Those qbs shouldnt be so close.. defintieyl have a hotspot under center area of them. the one front/left in diary pics look liek the light is lower and the paling is more pronounced at top? if not mistaken... if that looks to be the case, don't raise too much.. mybe 1/3rd of current distance? inverse squar law at work as you raise and lower. double is 1/4th, triple is 1/16th etc... or inversely increasing intensity if 1/2 1/3 of original distance etc..

That's nothing but natural fade, especially since the pistils are almost all brown. You should be checking the trichs to see if she is harvestable.... I'll bet she is! Good luck!

Some plant need a lot of nutrients in the middle of flowering, and they show you being yellow to early :) continue to give her a little bit N, with normal P-K, until last week, than flush :) bless!