So instead of a P deficiency, I'm actually starting to think it's more of a Mg deficiency, which is okay, except for the fact that none of the other plants are showing it, so something may be awry in the root zone.. I was thinking of adding a touch of epsom salts to a gallon of water and giving maybe a quarter of it to see if it bounces back.. What's odd though, is that's affecting ALL of the growth, not just old or new leaves.. It's not terrible right now, but with another month or so left in flower, I suspect things will get worse if I don't do something soon.. All of the plants get the same water from the tap and the pH is almost always between 6.4 and 7.1. Besides, I think the Kind Soil is just not up to the task of running plants this long.. Half the pot was filled with a 5lbs bag, and I added a couple more pounds of the super soil I made.. I also think the super soil I made is a little lacking in either P or Cal/Mg.. I'll add a little more lime and epsom salts/eggs shells next batch I make, which may be in a couple months since I only have about 15lbs of it left and if I keep having these kinds of issues w/ Kind Soil, then I may only use it as a last-ditch back-up if I can't wait a few months to cook soil.. There is a local place that makes a super soil that I'm using in my current grows.. Unfortunately, I tossed the bag, so I don't have any info on it, but it seemed more like EWC than a compost or like the super soil I made; very grainy but finer material, almost looked like a dark dark mulch..
Anyway, I'm gonna brew up the tea you mentioned because I have almost everything you mentioned, and we'll go from there.. I'm probably gonna cut it down a little more at first to see how the plants react.. I know you said to go at half strength.. The bigger photo that's deficient will probably get a half dose, but the autos will get the 1/4 dose..