I've had these two hanging philodendrons for several months. All is fine until recently one has been slowly yellowing and shedding.
My first theory is too much sunlight? It has been getting HOT lately. As you can see, both plants are close to a window. I made sure the plants hang in a corner, so it's not directly in front of the window, It is a south-west facing window. The other window is smaller and a few feet away. That one is a south-east facing window.
My second theory is overwatering? I use a moisture meter and water all plants only when the meter is in the red (DRY)
Possible Solution:
I water more frequently. When the meter is in the middle (MOIST)
I close the blinds for the nearest window because the room can still gets light with just the furthest window open..