Is the phosphorus deficency seen in my plants this...

hi spartan, sorry to disagree with folks on here, but that looks like K lockout to me, you can see that from the "uneven" "colorful splotches" appearing. Probably there was just one feed too many, anyway you're close to the end now so the only thing you can do is start watering with plain water only for the flush 2 week plain water flush. The "autumn colors" that's called senescence , and it will come once the plants have recovered probably withing 10 days. it's slight different than this you'll see (still scary to see though, so get ready lol) . Hope this helps ! 🚀