Is this powdered mildew or something else? Really stumped

So some of my plants have this white flakes on them. It's less bitty and more flaky, with some very large flakes. It's only impacted my jade and my elephant jade.

At first I did some pest treatments, just in case. I've also repotted all my plants recently and split a few to give them some more air circulation in case it was powdered mildew. Increased the drainage in all my pots and reduced watering, I do think I was over watering when I first got them a few years ago but they've been doing well since I figured that one out. One of my little jade cuttings I repotted is doing really badly with whatever it is, might have to bin it.

I've since been spraying down with water, dish soap and bicarbonate in case it's powdered mildew but It hasn't made a difference. Whenever I spray down (with whatever substance… Water, pesticide or they all look amazing for a few days and then this white stuff starts coating it again). What am I doing wrong?!

Is it powdered mildew? Is it a pest? I'm starting to become doubtful that it's either of those things as none of my other plants have been affected at all, they are all happy and healthy and everything I'm doing to help seems to not be helping. The water I have in my area is soft-slightly hard, could it be the water?

My plants sit in a very bright area, but I avoid direct sunlight with some mesh curtains.

If it is powdered mildew or a pest, please give me recommendations on how to fix!