What is the Problem with this plant?

Friend this is high temperature and low umidity

What's the EC of the water inside the DWC? That's the nice thing about hydro grows, that it's pretty easy to know if you're giving the plants too much or too little, just by measuring the EC over time.. If you feed them with, let's say an EC of 1.4, and it goes up in the reservoir over time, you know you're feeding too much (the plants take up mostly water) or there's a lot of water evaporation happening. If the EC goes down, the plant uses up more nutrients than water, and you should raise the amount of nutrients. If it stays the same then you have the right value. Secondly, are you watering with tap-water or with RO water (or a mix) and add calmag back? If tapwater: what's your starting EC? If RO water: to what EC do you bring your calmag up, before adding the other nutrients? I don't suggest blindly following the amount of nutrients, based on the manufacturers recommendations, as they can't know your exact environment, and different plants in different environments have different needs.. it's basically like if a dog-food manufacturer says "give one can to your dog a day" and they don't know if you have a chihuahua or a rottweiler - just different needs. happy growing!

Late in grow? i'd wager calcium, unless you have a cal-nitrate or similar component in your feed. use what's in your feed to eliminate possiblities. K-tox, Boron-def, P-tox can cause cal/mag def, .. don't think the K fits as well as that's not interveinal but has the spots and similar color.

Should be an intoxication by nutrient or too much water..