I don't see any nute burn, no tell tale clawing or wilting leaves. I would say more likely a diffiency or lockout. If you are in coco or hydro that ph is too high and will lock out certain nutes, its a good ph for soil. What are you feeding them and how much do you water?
im not op but you seem to forget that over feeding can show commonly as deficiencies. you constantly bring up lockout and that's so much more uncommon than you bring up. this is caused by over feeding. op if you cut your ppm, i guarantee you it will stop. in my ten years hydro experience, I've never caused a lockout once, even when testing 8.0ph in dwc, i have however overfed a TON, like everyone else has, and this exact symptom is the basic response to overfeeding period. lowering your ph .2 or .4 won't prevent lockout anyways.
your other diagnosis there isn't real. i regularly spill 1200ppm onto my leaves and you can too without burn. also, you only don't spray OIL products on light, hormones and nutrients SHOULD be sprayed in the morning light or before mid day, that's just how stomata work. the leaf magnifying glass isn't true and especially not when you drench a leaf with a wetting agent.
90% of the problems on the infirmary are more obvious than your obscure answers getting people to try ridiculous, unproven things that aren't wrong with their garden. this is basic nute burn and anyone growing this plant for years should recognize that quickly.
lastly, you can't see the fried, salted tips? did you zoom in the picture at all? he's got fried tips waiting to fall off from all that salt being fed. op feed water a couple times, then half feed and it will stop. it will never fix. once the leaf starts to die, pull it. that's all you need to do.
he also said this showed all over. you think he threw a jug of nutes across the room? you're so prolific with advice but it's all crazy. I've seen you make people waste money or think crazy stuff like a nutrient spill. it affected his whole garden because on his second big feed, they all burned a little. that first one was likely just sensitive. again anyone growing rooms for years has seen this exact situation play out a million times and op clearly is not very knowledgeable. you have to reevaluate what you're telling these people of you're trying to help them as half of these problems don't exist.
