Deficiency or burn

Looks like just a slight calcium issue. I add a 1/2 tsp-1 tsp per gal of botanicare cal mag plus and you could also foliar feed a calmag solution just ph and spray early in the morning but only once or 2x since you're so far in2 flower I'd rather not spray anything at all on the buds but have found it safe as long as u have good ventilation and let it dry off b4 lights out

Shes eating tooo much! Try more K, and magnesium sulphate! But that’s a slight burn, glad your paying attention though! Ease up and slowly start your flushing! K and Magnesium till the end! Molasses’s too!

You may have ran your nitrogen levels to high when starting to flower so you have slight nitrogen toxicity, the little brown spots could be a need for a bit more calcium or it could be some pests, my money is on needs more calcium.

Ph? What are the roots looking like?It looks like a Phosphorus issue, which into flower is more heavily needed, but calcium issues can cause that burn in the leaves too... You mentioned you changed the reservoir, but it is only affecting the one plant, are they separate? …