MistaOCanswered grow question 3d ago Your plant is currently in a phase where it needs increased nutrients for flowering — especially phosphorus and potassium. You might want to consider slightly increasing your nutrient dosage.
However, my first impression is that this could be a calcium-magnesium (CalMag) deficiency. You didn’t mention any CalMag supplementation in your grow journal. Depending on the quality of your source water, adding CalMag might be necessary.
I don’t think the issue is related to pH. With a pH-related nutrient lockout, symptoms typically don’t start on the lower leaves. In your case, the yellowing begins at the bottom, which is more characteristic of a nutrient deficiency.
Do you know your water values?