Leaf problem

That clawing is nutrient burn. And looks over watered as well. How is draining? 5 gallon should produce 1 liter of run off. Soil or coco? I'd flush it and check ec or ppm of run off.

That 1 leaf that is fading at the tip, that looks similar to light bleaching from too much light. Sorry i re-looked at your plant pix. The upcurling. Is it just on 1 or 2 leaves that are in close proximity to each other? Is it across your garden or just on 1 plant? Sometimes you can have a leaf pressed up against the edge of the tent and the leaf pushed up can make the tips look like that if you turn your plants periodically and didn't happen to notice at first.

Up curled tips are from hot nutrient mix. 550 to 600ppm is unlikely to burn your plants, so i would double check your TDS meter. Low TDS causing burn. The only thing i can think of that would cause that, is a way out of wack VPD, which would cause rapid transpiration, resulting in rapid uptake of nutrients beyond what the plant can handle. But you'd have to have like 30% humidity and like 85F to have that issue and you've said your temps and humidity are 26c and 50 to 60% RH. So i dunno man. Are you certain the ppm's are accurate?