Maybe you've already researched, but you can see the most similar example. In my opinion, it could be one of these 3. Since it's in the flowering stage, I think Nitrogen, Phosphorus, and Potassium.
https://www.growweedeasy.com/cannabis-plant-problems/potassium-deficiency
https://www.growweedeasy.com/cannabis-plant-problems/magnesium-deficiency
https://www.growweedeasy.com/cannabis-plant-problems/magnesium-deficiency