Anyone know what this could be ?

was going over my plant and found some weird grayish discoloration on a few leaf tips not sure what it is. Anyone have any idea?
I'm week five into flowering.

Can you get a better picture? Is it anywhere else on plant? does it rub off?

looks like powdery mildew or just slight over fertilized but should sort itself out.

I actually cut the tip off just to be safe but I couldn't find it anywhere else when I looked. Before I cut the tip off I tried to rub it off but it stayed.
I think I have a note burn or magnesium deficiency tho.