Q.Yellowed Leaves On Benghalensis Ficus Tree. Leaves Falling Off.what To Do?
I’ve had the tree for 9 months with few leaves lost. In the past week, leaves are yellowing and falling off. I’m following the instructions on watering and feeding per instructions.

Certified GKH Gardening Expert
Unfortunately, this tree isn't so easy to diagnose. There are many problems that this tree will experience, even, with very experienced gardeners that are used to this tree!
These symptoms can be seen with too much light exposure, soil that remains too wet, too little light exposure, soil that dries out, feeding issues (which I do not suspect at this time), and humidity issues. Unfortunately, at this point, it will be a guessing game. I would correct one factor at a time until you find what works for your situation. This article will help you to know what care these trees require:
https://www.gardeningknowhow.com/ornamental/trees/banyan/growing-a-banyan-tree.htm