What is going on? Droopy leaves for 2 weeks, had proper dry backs and last time to a point where the tips started burning because of it will I loose yield?

Short and sweet: My guess: water a bit sooner, at least for any plant showing droop. Feel weight of the pot of any droopy plant. Avoid getting that light in future. Why? How light are those pots? Looks like you are simply allowing too much time between irrigations. just beacuse you constituted it the same doesn't mean each plant drinks at the same rate. don't even go down that road of thinking you did everyhting indentically - that's impossible and it doesn't matter. if one plant is reacting differently that's all that matters in the moment. Not enough info here, but sounds like it's related to your watering choices. Can only investigate possible causes due to how you constituted the soil with trial and error in future grows. you're stuck with whatever is going on in the present. purple petioles is the LED lights or related to P, not Mg or Ca. I find it happens under LED no matter what. Any petioles exposed to more light have the red/purple coloring is a sign it's just the LED. Other symptoms would coincide if it were a nutrient deficiency, so it's easy to rule out. Leaves would have a blue tint to them and dark copper-colored blotchy spots would start to form starting at the bottom of the plant. Hard to miss if so. Lots of things have changed in that soil since you mixed it up. It's no long identical the moment time moves forward. Critical levels of fertilzier around the roots is the goal, not the ratio in which they are used in the plant, for several reasons related to how the plant takes in some nutes differently than others (different dependence on mass flow vs active transport). So a plant may be takign in more P or K than the next plant, which will change the ratio of nutse in the soil over time unless supplemented differently to offset it. plant dictates what to do.. not prconceived notions. prconceived notions can be a good starting point, but don't get stuck on them. if the plant is showing s symptom of some type, that is what should drive behaviour... not beliefs.