brown pistils

If you're seeing gnats already, get some of the yellow sticky traps and hang them in the tent to catch the live ones. If your growing medium is typically wet, get some Damascus Earth and cover the surface of the soil/coco. The gnats are likely whiteflies, not fruit flies. They need the moist soil to reproduce. I had an infestation last crop and I'm pretty sure the flies were dieing or pooping in my colas. When I harvested I didn't see any issues, but when I started dry trimming, I had bud rot in my biggest colas and ended up throwing out the entire crop. Fix your bug issue before it gets any worse. Some browning can be normal, especially in autos, but stress can cause it too.

how could them be pollinated? no hermaphrodite, no males... last week I take the lights down a few inches thinking that would be good for the plants, could be that?

Either burning from too much heat/light or it also looks like pollination may have occurred. It is not an insect problem. After looking at your diary, it seems temps and lighting are fine, so pollination would be my conclusion, they are way too young to be browning off pistils like they already are, unfortunately.

This is perfectly normal (and quite beautiful, too!). The gnats aren't doing anything and you won't see eggs or larvae because fungus gnats live IN the soil... and they live in very moist, wet soil - so this is telling me you're probably overwatering. Overwatering is NOT the amount of water you give at any one time, it is the state of being constantly wet... so let the soil dry out completely before giving water/nutes. You can get rid of the gnats (and I would recommend you do so) by using Mosquito Bits - just soak the granules as directed and use the water to water your plants... they'll be gone. Good luck!

it's four week into flower out of eight.

If it's still early flowering and turning color faster it's can be an excess of nutrients or too many lights.