One possible cause of browning on the edges of your ZZ Plant's leaves is the use of tap water. This is because tap water often contains salts, chlorine, minerals, and fluoride, which can accumulate in the soil and cause the tips of the leaves to burn and turn brown. Another reason for the browning could be due to low humidity levels. To combat this, you can increase the humidity around your plant by misting the leaves regularly.

Overwatering is the primary cause of yellowing leaves in ZZ plants. These plants do not require frequent watering as they can thrive off neglect. Only water the ZZ plant when the soil has completely dried out. Additionally, ZZ plants prefer low to medium light conditions and can suffer from yellowing and burning leaves if exposed to direct sunlight for extended periods. However, the plant can adapt to low light environments, so placing it in a dimly lit area may be beneficial.

ZZ plants are generally known to be resistant to diseases. However, like other houseplants, they are prone to pests such as mealybugs, scale, aphids, and fungus gnats. If you notice any of these pests on your ZZ plant, use insecticidal soap or other natural remedies to eliminate them.