Looked at your post & pics; it is a severe nute burn. Whatever PK booster shit you are using could be the culprit. High value bloom boosters in soil grows usually piss off the fungi by wildly swinging the ph out of range for absorption. PH of your nute solution is only half the story. You would need a soil probe to check the actual ph in the root zone.
So there’s that and it looks like maybe the soil had dried out as well. As hot rod says try just plain water for awhile. Water is really the only fix here. Your plants may not ever actually recover this late in the game but you could still harvest some decent buds in a few weeks. You have been given the same advice by at least three members....