The plant is skinny but has new growth with beginning buds. The plant next to it is fine.
Why Is My Gardenia Yellow
Certified GKH Gardening Expert
Yellow leaves normally signal that the plant is under some type of stress. In order to remedy the problem, you must first try to pinpoint the issue. This article should help you with that: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/helping-a-gardenia-bush-with-yellow-leaves.htm
This article may also help: https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm