I have a ‘Sungold’ Buddleia and the leaves keep getting eaten by something and go yellow what is the problem.
It is planted in sandy soil next to a Davidii Buddleia which is absolutely fine and doesn't get eaten
Certified GKH Gardening Expert
If you can include a photo, it would help me to identify the issue. It sounds like, though, that the cultivar next to it has a disease resistance unlike the one beside it. It sounds like shothole fungus.
This article will help: https://www.gardeningknowhow.com/plant-problems/disease/shot-hole-disease-fungus.htm