Yellow leaves at the top. Does not appear to be grafted. Purchased about 4/5 years ago and never pruned.
Yellow Leaves at the Top
This article suggest some possibilities: https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm
To get more specific information, you'd need to provide as much specific information as possible, such as the name of the plant, its size, amount of light, and particular appearance of the leaves, i.e spots, area of leaf that's discolored, shape of leaf, anything else you can think of.