Betta Fish: Day 3 of Tank cycling: what is this white powder floaters in my tank water?

I got a new tank for Brutus my betta. According to Gemini, I should cycle it for 21 days(I'm doing a fishless cycle), so I'm on day 3 now. I've been seeing these since day 2.

(A quick back story)
My betta is currently in a nano tank. When I set up that tank for him. I was clueless and sort of panicking because he was in this very small lego brick cointainer when he was gifted to me. That time I just looked online bought stuff like Romblom pebbles some plants but I never got these floating powdery mess. I didn't even cycle his current tank.

and now, a month later I'm moving Brutus to a 50cmx33cmx18cm shallow, I could say, I'm doing better research now and bought Aqua soil and white coarse sand.
I did pre clean my sand before place it in my tank. I kind of have a feeling that this might be dust??? Idk. The glass also keeps getting this rough residue that is SO hard to clean. It forms in the waterline, Below the waterline, and near the sand.

The few plants i planted also keeps getting dusty.
Any tips how I can get rid of this? Or is my new tank ruined?