Hey pal
I get this a lot lol
So, if it was say a def, you'd see it up top more or leaves completely drained.
Your leaves show that your plant was using them as food. The crispy bits is from the plant completely draining it from fluid
So, if your soil has gotten dry. To the point that water comes out the end, been a fiber pot, you'll know by felling the underside of the Fpot. If it's dry and then gets wet after you feed. It's dried up too much.
This is just your plant feeding on itself. It's very common..
No lack of food. Just lack of fluids in the sub. So, she's been sucking dirt and those leaves were closest food source. Hence why they are only showing. It can cause you to lose pigment in your leaves if it happens too often.
There is a thing called crop steering. And drought is 1 of the ways ppl do this. But you shouldn't do it In pre flower. It's more used In fattening. As it forces the plant (dig deep) into its reserves and makes bigger buds. (Not saying this was your choice just pointing out it's very common, well it is with my crops lol)