Hey there Germano, you have calcium and magnesium deficiency probably from heat stress and maybe light stress. I dont really know anything about your lights but i can see the brown and curling inwards from the side of the leafs (that's magnesium) and sometime some brown spots in the middle of the leafs (that's calcium deficiency). So what you need to do is get the temperature of the root zone as cool as possible , water with colder water , then add more air flow to get the overall temperature down, maybe even get an evaporative cooler if you can. Finally you do need to add cal mag otherwise the problem will spread add 3ml/L cal mag, and make a spray with 3ml/L cal mag and spray at lights on every two days for ten days. If you do this the problem will stop spreading and the plant will recover in 10 days, hope this helps ! 🚀