Yellowing of the leaves...

Yeah, you’ve over fed them is all. They’re super dark leaves say nitrogen toxicity. Your getting real close to finishing the grow it looks like. You might want to think about just giving water for a week and see where it’s at. Your going to want to put a good flush on it being as your over fed this close to harvest. You don’t want to taste that stuff.

If you overfeed, I would proceed as follows. Best if you have osmosis water and mix the stale water for 24 hours (after 24 hours the chlorine has evaporated somewhat) to an Ec value of 0.2. Then add Cal / Mag until the Ec is 0.4. This is your source of water, so you can flush. At the next pour, start with a quarter of the feed dose.

That's a nutrient toxicity or a lockout, either flush it or just try watering with ph'd water, that's less aggressive