Foliar Damage on Varigated Red Twig Dogwoods
This looks like the early stages of sawfly (larva) feeding. They are not uncommon and aren't usually of great concern (other than cosmetically) on this shrub.
If you have to treat, spinosad should work.
(Though it looks like a caterpillar it's not so Bt would not work).
A similar species here: https://extension.umd.edu/hgic/topics/sawflies-flowers