Pothos leaves turning yellow commonly indicate stress from one or more care issues. The main causes include:

• Overwatering: This is the most frequent cause. Yellow leaves combined with blackened stems or soggy soil often signal root rot caused by too much water. Pothos prefers its soil to dry out between waterings. Overwatered roots become brown, slimy, and can kill the plant.

• Underwatering: Yellow leaves paired with droopiness and dry soil can point to insufficient watering. Leaves may also curl and wilt.

• Insufficient light: Pothos thrive in bright, indirect light. Too little light results in yellowing leaves. Direct sunlight, however, can scorch leaves and also cause yellowing.

• Temperature stress: Pothos prefers warm environments (70-90°F or 21-32°C). Exposure to cold can cause yellow leaves and leaf drop.

• Nutrient imbalance: Either a deficiency or excess of nutrients, especially nitrogen and fertilizer salt buildup, can cause yellowing.

• Natural leaf aging: Older leaves sometimes naturally yellow and fall off as part of the plant's growth cycle.

To fix yellowing leaves, adjust watering habits to keep the soil consistently moist but not wet, provide adequate indirect sunlight, maintain warm temperatures, avoid over-fertilizing, and remove yellow leaves to encourage new growth. If overwatering caused root rot, repotting in fresh soil after trimming damaged roots may be necessary.