turned yellow, what's the problem?

Maybe too much K? it's odd because it's glossy up top but looks like n-deficiency at bottom. K-tox might be your best bet. if in soilless/hydro context, if mixed fertilizer contains 200ppm K there's a good chance this is the problem. can't give you a simple threshold for soil, though.

So my thoughts: tips of the upper leaves are curled downwards (clawing), leaves are glossy, dark green, shiny, some tips are burned, all indicates Nutrient toxicity. And i bet you are thinking "wtf, how can it be a toxicity, i can clearly see a deficiency " and you're right. The problem is you probably hammered in SO much nutrients the plant just can't uptake anything anymore. imagine, as the gates of the plant are SO crowded with soooo many people, nobody can move in, or at all. Whatever you do, more fertilizer is not the answer you are looking for. I would guess too much fertilizer o r very, very wrong pH. I can't tell what it is but it's probably the first. Only thing you can do is flush the pot. until you have like 1-3L run off (depends on how big the pot is), to wash out all the salts. best thing if you can flush with pH water pH 6 should be fine for soil, demineralized water usually got a pH of 6 (if you live in europe otherwise idk) if you have nothing else. This happens to all of us, we all did this... don't worry, good luck!

Hello mate, I think it's only a potassium deficiency, you are a bit further along the flowering phase but you might do a difference fixing the nutrients now. Good luck and happy journey!

If not first signs of lockout from toxicity, then i would guess : plant redirects energy and gets rid of leaf , which constantly sweated while touching soil.