One of the most common reasons why mother of thousands leaves turn yellow is due to a nutrient deficiency. If your plant is not getting enough nitrogen, phosphorus, or potassium, the leaves will start to turn yellow. Another possible reason for yellowing leaves is too much sun exposure. If the plant is getting too much direct sunlight, the leaves will start to turn yellow and eventually brown. If you think either of these might be the problem, try moving your plant to a different location or giving it more or less water.
Yellowing leaves can also be caused by pests or diseases. If you see any small insects on the leaves or stem, they could be sucking out the nutrients from the plant and causing the leaves to turn yellow. You may also see spots on the leaves which could be an indication of a fungal or bacterial disease. Treating pests and diseases early is important to prevent them from spreading and harming your plant further.
If you're not sure what's causing your mother of thousands' leaves to turn yellow, take a sample of both healthy and unhealthy leaves to your local nursery or Cooperative Extension office for testing. They'll be able to help you determine what's wrong and how best to fix it!