Light stress or calmag deficiency?

the damage is so advanced, it's even tougher to diagnose even if in good light. Looks like you ignored a potassium deficiency for weeks. At this stage of development, if it was light, you'd see some symptoms in the colas. bleaching, singed pistils as they were first developing etc.. .other ways to rule out light - was growth perfectly fine under same intensity before? Did you ramp it up at some point before the damage showed up? foxtails and knobby colas could also indicate too much light. Extra close nodes, if it was too intense while the internode formed. Damage relegated to the top for what should be fairly mobile nutrients is another tip-off.