Loosing leaves

Looks like Nitrogen Toxicity or over/underwatering. I would suggest to lower the dose of Nitrogen and/or try carry the pot and see how the water is inside, if it's watered to little.

It's very possible she's ending her life cycle and this is normal decay. It does, however, strongly resemble overwatering, extreme humidity, and nutrient lock. Underwatering is possible too, but not very likely. Test your runoff for funsies and lower it if it's much higher than your feed. If so, just feed with pH'd water for a couple feeds. If it's very, very high (over 1400), do a flush. Really hope this solves your issue, best of luck!