Yellow Leaves during flowering.

Up to a point, lower fan leafs are expected to go yellow, as the plant eats up the nitrogen. So yes you should give her some, divided in 2 or 3 waterings, just enough to keep her going for the next couple of weeks, than switch to potassium based. Keep an eye on cal mag and phosphorous and it's all good.

If it’s the fan leaves I wouldn’t worry it’s normal when the are in late flower that’s what I was told

Hey friend, how's it going? From what I see, it looks like a nitrogen deficiency. It seems like the plant should have given some signs of that on the leaves. But nothing is lost, just add a little more N in the next watering, with well-regulated pH, and everything will go back to normal. Some leaves might not recover, but that's normal. Good luck with the grow!

If you are in the US or Canada get some Recharge by Real Growers. That stuff helps the soil feed the plant efficiently and makes the leave green AF!

I often have to add some additional nitrogen for the first 3 or 4 weeks of flower above what is included in most "bloom/flower" fertilizer blends.