I agree, the color of the leafs don’t indicate any nutrition issues in my opinion. Just needs more room to stretch their legs.most certainly root bound... just look at that plant and then try to imagine the mirror image down below in the root system. If this was not in a smart pot I suspect this plant would have died already, but I think it can still be saved. Transplant it immediately into at least 10 gallons of soil, and when you manage to peel the present bag away from those roots, use your hands and pull those tightly knit roots apart a bit before putting them in the new soil. This will help ALL the roots in that tangled up mass to get a fast fresh start in the new soil.
That being said, I have to say wow! Great job @WCJ11 on getting that huge plant this far in that small amount of soil. You appear to have quite the green thumb... just overlooked how big this thing could get!
Thanks for jumping in Em!