Possible pm?

NOT powdery mildew, which grows in "clusters" and has associated webbing. Those tiny white "dots" look like trichomes. The bigger creamy brown marks/dots look like insect damage or burning from spilled fertilizers.

The tiny dots are trichromes looks like. The big white spots could be from leaf getting wet under the light. I keep my humidity in a 40 to 60 range. I never have any issues since I started doing it related to humidity anyway.

Looks to me like you've got an unwanted guest having some lunch. It's certainly not powdery mildew - spot is MUCH too small and doesn't have the powdery texture.... If I were you, I would get some Dr. Zymes Eliminator or some Spinosad and spray as directed just before lights out... either one of those (both are organic) will kill the adults/larvae/eggs of spidermites, aphids, thrips, or whiteflies which are the usual culprits. Good luck - and DO start a diary!

Although. I don't like the look of that white blob on it. That. And there's no diary to see the plants overall health. As if you have PM, you'll more than likely see other signs your plant will show from lack of ven and other factors.

PM it could be. How to easily find this out. Bang a pair of gloves on. (Or wash your hands after) if it's PM, it'll rub off with your fingers. But, if you've used any synthetic nutes as a foliar spray. Most likely its down to the salts in that. "Which in itself will also rub off"..if I had to give a guess. It'll be from the latter. Just salts. Good Growing

Did you spill any fertilizer or water droplets on the leaves could also be mold or bugs work through your trouble shooting. Remember if you spilled anything check for creepy crawlies under leaves and around plant and soil and dont over water