Yes, there are tiny black spots on the undersides of the damaged leaves, but no bugs that I can see.
You really shouldn't be seeing tiny black spots on the underside of any of the leaves. This makes me suspect that you might have thrips. You need to take a close look (loupe or magnifier) and see if those specs are moving around.

If you need to treat the plant(s) again, move them out of the sun or do your spraying at night.