All 3 of my pepper plants have developed white spots on their leaves. I thought its fungi so I've been using some neem oil (mixing 2 table spoons in a gallon and watering the roots and spraying over leaves after sunset). Unfortunately it has got worse.

I've attached pics for all 3 of my plants: bell pepper, serano pepper & thai chillis. I live in SoCal. If any of you have experienced this before and happen to know the solution, would really appreciate.