Hmmmm... i can't say for sure about that. I would point to switching to bloom nutes a full week to ten days after you see them starting to develop. Maybe you did. I have made a point to wait a bit to make sure my plants nave all the Nitro they need to finish flower. They really don't look too bad, but it looks ike they have been yellowing for a little while now. I use microbes in my feeding schedule and that really helps in an organic nute set up like GO. Have you thoight about using a little Recharge or something similar? It helps to buffer nutes providing what the plant needs when it needs it. Also, Biocozyme helps break down unhealthy roots into additional nutrition. These two things have helpped me in the past. So much so, they became a part of my preventative and the plants have been looking awesome. My Thai Sticks that went for 18 weeks really were yellowing out a little early and made me nervous. So I put a little top dressing of some bone meal to provide a small N boost, even though in flower. It didnt help much, lol. Plants still turned out awesome. I wouldn't be afraid to give a little N but make it a synthetic N something plants can absorb and use it right away. Just a little, perhaps quarter stregnth.
Hope,this info might help. I like ve that donky dick you got going on in the far right back ground. "Yuge!"