Purple spots????

What is the ph of your water ? Reason of question is that this seems to be a problem caused by less magnesium, but the cause of this can be that the strain isnt able to use all of his nutriciens because of a wrong ph.

https://420life.com/wp-content/uploads/2021/10/Marijuana-Leaf-Deficiency-Chart-scaled.jpg here is a chart to help you decide. Next time when asking show the whole plant and where the leaves are on the plant. Eg. top. middle or lower growth.

Maybe is both Ca and P deficiency as these two interact with each other inside the plant. I think giving her a rich cal/mag and p/k supplement will do the trick. Stay strict to wet/dry watering circle. Good luck!!

Phosphorous deficiency...........the spots with the damaged leaf edges beginning to show are the clues. It is not calcium related, the spots are too big and it certainly is not wind burn.

wind burn

low Ca mixed with low temps at night causing the 'autumn' color

The plants beg for calcium and magnesium around week for of flower. Make sure you give plants nitrogen until around week 3 and week 4-5 the plants need calcium and magnesium for building new cell walls. Aka buds. And then 6-8 they want higher levels of potassium. Hope this helps. Also I don't mean just these things but these are the things the plants are wanting more of at these stages of flowering

Calcium deficiency most likely. But from one leaf and no informationb that's the best you get

hey 👋 seems ike P-k and Mg def, + too low temp at night