what causes white spots on leaves that is not powdery mildew?

Question

I have numerous plants with white spots on the leaves, like radio red salvia, and mint

Answer 1

White spots could be a fungus, Mealy Bugs or Scale or even sun scorch from overhead watering.

https://www.gardeningknowhow.com/plant-problems/pests/insects/what-is-soft-scale.htm