Deficiency or heat stress?

Whitout infos is hard to help you. From what we can see,also your light is not at the proper height(judging on how she's stretched) and i bet you do not control water ph! is really important bro. Good luck 🍀

Need more information, no diary linked and no info on what the setup is... temps feed + schedule water rate + schedule RH medium composition PH EC PPM Lights, distance, wattage, type fans It looks as if your growing in a metal container and in just coir/peat?? If true. the coir will need to have been buffered before use or it will rob the feed of all its calcium and magnesium. add calmg if not buffered. Did you amended this medium before use? Coir is mostly void of nutrition, has to be boosted, peatmoss has some but not a lot this could also be a root issue, lack of oxygen or PH. If using PH'd water it will react with the metal container over time. No idea if this will affect the plant or not, probably just rust and wreck your bucket. rust or iron oxide is not toxic but also not good in excess. best of luck

Is this a Signs of Calcium deficiency?