Q.Lemon tree losing color
My indoor lemon tree leaves are losing color and are falling at a high rate. What is the cause? It started about two weeks ago and it is not stopping.
Thank you.

Sudden leaf drop can be due to insects, disease, excessive fertilizer or root rot due to over watering.
Here is some great links that will help you with the issue and refresh you on the care requirements.
https://www.gardeningknowhow.com/edible/fruits/lemons/lemon-tree-leaf-drop.htm
https://www.gardeningknowhow.com/edible/fruits/citrus/growing-citrus-trees-indoors.htm
https://www.gardeningknowhow.com/edible/fruits/lemons/how-to-grow-a-lemon-tree.htm