Nitrogen claw on cannabis leaves
What it looks like
Leaves are dark green and the tips claw down. This is too much nitrogen, not a shortage. It is common in early flower if veg feed was never cut back.
What usually causes it
Cut nitrogen. Plain pH-adjusted water for a cycle, then a lighter feed. Clawed leaves stay clawed. New growth should come in flat.
Check this first
Dark, shiny leaves curled down like a talon, usually after a heavy feed. Back off the nitrogen. Claw from too much is the opposite of the pale leaves of too little.
This is identification for a home grow. It is not a pesticide label and not medical advice. Follow your local law.