Q.I Have New Young Leaves Growing In My Monstera Family And Noticed One Of Them Turned Yellow And Black Before Even Opening. What Co
uld be the cause of this? The leaf grew at the bottom. At first it was green and now it’s almost pale yellow with black spots. Other young leaves look find.

Certified GKH Gardening Expert
Unfortunately, your photo did not come through. It does sound like an infection. This is most likely due to soil that does not have a chance to dry out between waterings.
I would treat with a fungicide, then make sure that you wait until the soil is completely dry down to about 2 inches between waterings.
Here are some articles that will help:
https://www.gardeningknowhow.com/houseplants/swiss-cheese-plant/repotting-cheese-plants.htm
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm