Is that Happy Frog? I dont think it has much in it for a plant that size to eat. My breeders are in HF and I have to feed them every other day, but they are in small bags. Ocean Forest seems to have enough in it to carry a plant thru veg. My guess is the new growth that looks ok is sucking the life out of the older fan leaves either because of lockout or because there is nothing in there to eat. I would transplant it into a bigger pot with Ocean Forest, trim off the ugly spots and start to feed at 1/4 strength