White spots on pachysandra
We do not think that this is a disease or insect pest and so is not of concern.
We suspect that these plants are growing under an evergreen tree which may be dripping some sap? It looks like dried sap to us.
We would suggest pulling the vining weed shown in the upper right corner of your first photo.
It looks like it might be Ampelopsis/Porcelainberry, which is an invasive vine.
Here is our page on it: https://extension.umd.edu/hgic/topics/porcelainberry