General improvement.

FC48000 - 18" 66-70% power and 18 hours per day. I use this light in a 4x4, too. You may still need minor adjustments. The hanging distance is probably best to keep similar unless you use an app to verify a better overall coverage wall-to-wall without sacrificing overall average of the readings (many locations, same distance from light) Adjust dimmer based on internode length. If too stertch, it needs a bit more. The reason i suggest a height that works for "66%" is beacuse when you go from 18h to 12, you need 150% of the wattage to maintain the same DLI -- inversely proportional to hours of operation. Daily Light Integral - read the wiki, get the gist even if bad at math. The gist is good enough. I see you are using autoflowers, so you you don't need 100% power in a 4x4 with this light. I actually run mine on a 16/8 cycle, so it needs a bit more power, but it amounts to same 35-40 DLI, give or take. As long as you max out DLI relative to your local variables, you'll maximize the growth rate (all other factors the same). Your local variables will cause a different 'max' DLI. you'll need some trial and error to fine-tune it. If you supplement co2 you'll get higher growth rates as well as certain other methods of growing compared to soil. These numbers only get you in the ballpark and not meant to be read in a 100% literal way. they are tools to guide you along with observations from the plant, of which, what the plant says is most important. I wouldn't be surprised if you need a couple more inches of height or a bit less power. that is a very strong light and i tend to err on high side with an educated guesstimate so i know I'm dialing back from "too much" and more confident i am "Given'er all she's got, Captain!" also, based on diaries, you need to fix your watering habits. Never water an incomplete portion of the substrate. this only leads to problems down the road and your plants are plenty big enough to drink from the entire pot. Only in the extreme case of a tiny plant and huge pot do you want to water a smaller column, and even then you want to mamke sure that moisture goes all the way down. This promotes deeper roots and avoids superficial roots. Use more perlite or similar. A heavy soil should have 50% of such drainage amendments. coco can go with 33% because it holds proportionally less water per volume than most potting soils or a sphagnum peat moss substrate. Always water entirety. Always wait for top to dry ('they' say 1" in soil). At the very least stic to that in vege for robust root growth. More frequent irrigation/fertigation may be useful later on, but you better only try that when you add more perlite in future or else you'll just rot your roots or grow funky shit under the surface. Summation -- Fix the light firss, then see how it reacttts/ That might be the sole cause of what you see. the pant in pic 6 may be a totally different thing.That may end up being a virus or mutation etc... If the leaves never kick that shitty growth and the rest of the room doesn't exhibit any of those symptoms, it's possible a piece of shit plant for one reason or another that you cannot control.. Hopefulyl it is from watering habits or slight ratio imabalance and it improves. For all the others i'd wait and see how a better light cycle and watering habits affect them over the next 1-2 weeks. This one you may want to investigate further. Make sure pH of runoff isn't soemthing really wahcky -- runoff should be different. It's dirty water with excess minerals in it, so be forgiving when reading the measurements of runoff pH or EC. It does look like that particualr pant in picture #6 has a root zone issue brewing or simply a mutated plant if everything is kosher.

Check ph and they dont need feeding for one more week at least, some show heavy overwatering and ph imbalance symptoms, calmag in small doses and root stimulant is all you need, maybe even for two more weeks, later start thinking about feeding.