Welcome to RIU
What nutrients are you using? What feed/water schedule, ppm/ec, pH?
The yellowing leaves look typical of the plant reusing nitrogen from those leaves to support new growth. I get that in the lower/older fan leaves in my outdoor as the season goes on. Yours doesn't look too problematic.
I see some small white spots on some of the green leaves that may or may not be caused by bug pests. Check thoroughly under those leaves for bug pests like spider mites. They look like tiny almost microscopic little brownish orange balls, just barely moving. As they become more advanced they make very light webbing under the leaf, and then the leaves start looking much worse as that webbing starts spreading over the plant. I just see what might be very early stages indicated by small white spotting on top of green leaves. It might be nothing, but it's good to check thoroughly.
Good luck! Peace