Losing bottom leaves

Only one of my plant is losing leaves. They are not big fan leaves and they are at the very bottom of plant. They fade to a pale green/ish yellow and come right off. Some days I lose 0 leaves other days 7 of em. It doesn't look like nitrogen deficiency. Thought it was and gave some N and started to talon on me. Is it from lack of light due to canopy thickening and filling out more?

I wish I could be certain but I'm a newb. I think it just might be the low levels of light it's receiving. I am not sure tho I'm having the same problem. With the lower leaves turning yellow. If you could tell me what this is I'd really appreciate it.

Could yours be from nutrient burn or ph fluctuations?

Lol I don't know. She is on her 4th week 12/12. I was thinking it was norm but I'm not sure.

Here is a full pic.