Might be leaf miners and cutter bees. Maybe slugs or snails. In my experience with the Purple Leaf Sand Cherry it is attractive to many insect species but none in large enough numbers to be much of a problem.

this late in the season.. who cares.... the leaves will be falling off soon enough ...

other than for the knowledge of course...

ken

I get japanese beetles on mine.

I do see signs of some kind of leaf miner, but nothing else identifiable. Not leaf cutter bees nor Japanese beetles this time, though those pests can certainly be found on these plants (along with most other pests and diseases known to plant life).