Start with what you know needs to be altered/checked and use the process of elimination while you're going. In my situation leaves like that mean wind burn (Looking again probably not also) but you've got a few things going on that need to be adjusted by the sounds before another diagnosis. Up...
Underfeeding and check pH. Looks like the plant is using the nutrients in the leaves to survive but I'm no expert, just going off what I've seen in front of me in the past.
It comes down to the plant/strain in the end and more focus on how much light than nutes. If you see any tip burn over the next few days bring the ppm back down and if really bad complete flush. I'm at day 56 of a Chemhead, with bug issues and it's barely reached 600ppm throughout bloom using
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I love the AN 3 part ph nutes. When you have your shit dialled in a pleasure to work with. Only issue here in Aus is supply. At the moment it can be hard to find.