Black mold like on Holly’s, wax pivot and red tipped photuna
The black substance you see on the leaves is called sooty mold. We see that there are scale insects on the stems of your plant. Scale insects suck the plant sap and secrete a sugary substance called honeydew. The mold grows on the honeydew.
This looks like cottony camellia scale. You can manage this insect with the application of horticultural oil. https://extension.umd.edu/hgic/cottony-camellia-scale-shrubs