What’s causing plant to burn?

Thats an easy thing here,,, just overnuked😱

That's when your hidden problems always show their face (in flowering). Some people do so much nutrients like they're a mad scientist Just thinking where these grow naturally they don't have this person coming along adding nutes. Whatever you're giving it back off. I only use tiger bloom in flowering with tap water and I only use half of what they recommend. I don't even add calcium for example because my tap has that. Usually the upper fan leaves closest to lights show the problems first making one to believe its the lights. I think you're giving too much flowering nutrients, not sure though.. but if I was betting money on it I'd pick that. You could flush it with about 8 gallons of distilled water then see if it gets better..

its hard to really say because the blurple lights make it difficult to see. Take photos with out the grow lights on, use flash or some other neutral light

It seems to be a mobile nutrient (affecting fan leaves and lower growth working its way to newer growth) however the deficiency/lockout combined with extra light is pushing the plant way too hard right now. Cut back the power and raise the lights up. Then start trouble shooting everything else. The more light you give your plant right now the quicker she will die.

That’s not light burn. That’s for sure

So to get an answer you need to give some info: How far away are lights? What, how often, and how much are you feeding? How often and how much are you watering? How wet is soil when you water or feed? What ph are you using for water and feed? What substrate are you growing in? Is it soil, soil less mix, coco coir, live soil, basically what's in the pot? What is grow room humidity and temperature looking like? Before you trash it we should try to work out what the issue is so you don't have a repeat. Plant is f@cked and won't produce much, but if you can stabilize and prevent it from dying at least you know where you went wrong. Also first picture looks like the plant is wet, did you mist it with lights on? Could burn your plant (acts like little magnifying glasses) but would not cause the issue you are having. I'm just curious why it looks wet?

Without any details about substrate/PH in/ nutrients used and how much. It could be many things. You probably did something mucho wrong to her at some point. If you don’t already take notes on your grows. I suggest you find a way to keep track of what you do so that when things go wrong like this you have notes to look back at and piece things as to why it went south. So take it as a learning experience and don’t do what you did next time. Take notes. Cheers. 🤙

This is Nutrient Lockout/Burn! Better you start a new grow :/

This is excessive nutrition, not lack of them. My advice start all over, this plant is 10 g max at the end, you can do better without mistakes.

Hard to tell in the blurple lights, but that looks like a bad PH problem causing a massive toxicity due to nutrient lockout. I think it might be too late to salvage since I can see your well into flower=(