contrary to a lot of the fucking jokers on here (apologise to sensitive fucking jokers on here) , there is indeed too much available light and most certainly (usually undisputed) too much heat. I have found DWC can survive the onslaught of light, but flood/drain and soil can really suffer by not getting the nutrients required. Whispy buds will follow!
popcorn buds in my experience come from poor basic variables such as temp, relative humidity and light proximity.
A lot of people think their environments are dialled in because the plant is veg'ing brilliantly. they are easy as hell to veg nicely! When switching over to flower though, lower RH and temps + lowering of light will make a huge difference for yield/quality. Like all things, there are no magic numbers. Lots of sitting and observing will make a difference. really try and reduce that humidity for flowering, which might even require changing your setup. I had a lot of humidity problems in my new place after being a die hard SOG flood/drain gardener. Now I use DWC to combat humid and warm root zones that were messing up my yield and quality at the same time as reducing RH at the plant height which was hard to keep below 70% even with aircon! I used coco instead which was more resilient to high temps / humidity first, and it was better than clay, but still not half as good as It had been. Hence the entire system change. DWC is back to business, and when dialled in, not that fiddly really. I don't touch it until res changes every two weeks.
I usually mess with shitty genetics and still get really good quality buds. smell amazing, lots of trichomes, as dense as a no name gets. environment > genetics ! (In my experience, quality unknown genes grown well will smoke better than great gene's popcorn)
/tirade