The ZZ plant has developed dark round markings on the stem as it has become more mature. Is this normal?
Certified GKH Gardening Expert
It is possible that some markings are normal, but if they are dark and spreading, I would say it could be fungal in nature. Here is an article that will give you more information: https://www.gardeningknowhow.com/plant-problems/disease/treating-root-rot-gardening-tips-for-housplants.htm