Cactus soil, which is sandy in nature, is too dry and can’t retain enough moisture. Tweak it by adding peat moss or coco peat with compost.
“Potting up” is an annual transition for Monstera plants. If your Monstera is potted in an 8-inch diameter pot, it needs to be transferred to a 10-inch pot.
Young plants generally need to be transferred to a slightly larger pot every year in late winter or early spring. Even if your Monstera is fully grown, repotting is still recommended.
These are symptoms of soggy soil. The cause could be overwatering, using the wrong type of soil, and/or using the wrong type of pot.