Some PM advice for a new green thumb

[Cremefreeshe]

Hey all, hopefully this is the correct thread. I'm having some issues with what I believe is Powdery mold/mildew that I've seen from time to time. I'll attach a few pictures. The plants are still in their first month but I noticed the splotches right away. I gave it some time and increased the air flow however it seemed the leaves needed a milk spray. I tried 60water/40milk and it left behind quite a good amount of residue. (1% milk and clean water) . TLDR is this the scenario where you would all cut your losses or go through and see if their saveable. I'm more just worried about spreading to new plants that I'm getting ready.
They are getting 18sun/6 off and are in full light and air flow during the milk spray

That residue is the milk. I am thinking next step I'll do is wash the leaves but I'd rather wait on advice so I don't fuck them up more incase.

 

[Hydroholic]

I see the milk splotches no mold. Fill those cups up with soil. Your plants will be happy.

 

[Nunyabiz]

Whatever problem you're having is probably due to them growing in a thimble full of soil at the bottom of a cup.

 

[Cremefreeshe]

Genuine ty for responses, theyve been moved to 19L buckets with the proper soil mix and drainage rock. I will keep an eye out for any further issues. Got stuck with cups when covid shut down my local hardware store. (Shitty reason I know)