I don't know bud. N tox or nute burn I think causes leaf clawing downwards. I've had that. I've had leaf edges curl up like that a little and it was my light being to close. Heat or too little water can do it too. Most of the end of life dying leaves pics I've seen the leaves looked crappy but I didn't notice them being curled. But maybe they do.
Just looking at the pics and my very limited knowledge I'd guess light or heat stress.