what are those tiny white things

What you’re seeing is a cannabis mutation called trifoliate (or whorled phyllotaxy) . Normally, cannabis grows with 2 leaves per node, opposite each other. In your plant, it’s showing 3 leaves per node a genetic mutation. This doesn’t mean the plant is “bad” many trifoliate plants grow perfectly fine and can even be vigorous. Sometimes the plant will stay trifoliate for life, sometimes after a few nodes it will switch back to normal growth. Meaning for your grow: Nothing harmful just a rare growth pattern. It might grow bushier with more side shoots. Yields and potency are not negatively affected, sometimes even slightly improved because of extra branching. So basically you’ve got a mutant baby, but in a good way.

got a scope for flower? ... probably trichomes.

Unfortunately, I can't zoom in any closer, but from what I can see, that's real powdery mildew. Immediate action: apply lactic acid bacteria to the leaves. They're almost everywhere, in unpasteurized milk, in sourdough, in unpasteurized sauerkraut juice, in bread drink... Just mix 1 part milk/other additive with 5 parts water in a spray bottle and spray it on for three consecutive mornings just before strong sunlight. That should help. BoomBoomSpray (BioTabs) and Alphaboost also work well, by the way...

Hi mate, from what little i can see by the photo mate it just looks like passive dust, could they be any dusty areas nearby that is bring dust in via a fan? Main thingnis dont over oanic just yet mate, guve her a gentle wipe down with water to begin with and see if it comes back, but dont worry just yet and defo dont give up on her, she looks as healthy as she should mate. You are always wwlcome to Dm for further info if needed. Please mark this as the answer if you feel i have helped in any way.