Q.What Is Wrong With This Sapote?
this is a seed-grown plant, about a year old, has been inside to date. Until recently, the plant seemed healthy. About 2 weeks ago the leaves started turning yellow, with brown dead spots. The new leaves are green. While it looks as though something has been spilt on it, I don’t believe that has happened. I have just given it to someone who can put it outside at least during the day. Can anyone tell me what may be wrong, and what to do about it?

Certified GKH Gardening Expert
That looks like a bacterial infection. Bacteria thrive in wet soils, so make sure that the soil has a chance to dry out between waterings. Feeding and applying a fungicide will help. Old markings will not resolve, but you will know that treatment is working when the disease stops spreading.
Here are some articles that will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/edible/fruits/sapodilla-trees/growing-sapodilla-fruit.htm