could it be light damage?

I think you are under feeding them at .8 EC. They might just want more nutrients. Also PH for soil is 6.4-6.8, 5.8 is a bit low, I'd bring that back up and add in some microbes to help replenish the ones that may have been lost to the lower acidly. Good Luck!

Not the light, no way. Anything under 1000 aint going to cause light burn unless you have seedlings. Thats a nute or Ph issue causing lock out. or Humidity is too high and plants arnt transpiring enough so are not uptaking enough nutes. Drop ya Humidity to around 50-55% if its not there already and give the yellow fellow a good feeding, should perk up once it starts sweating a bit more and up taking those nutes.

Remember green is the normal color for a plant in veg and or early to mid flower depending on the strain. Yellowish colored leaves are not normal. Be aware that some plants are heavier feeders than others. And when you add anything new to the environment it's always a good idea to introduce it to your grow space a little at a time, with lights dim em if you can and gradually increase the intensity until your at the desired intensity level. So in short I think the plants that are a little yellowish are hungry.

You can tell if it's the lighting by how tired they are at the end of the light cycle. If they are still praying at the end of 18 hours they need more light. If they are drooping 3-4 hours before lights out they need less light. Overwatering/underwatering can cause drooping as well. Have you been checking your PH? Looks like a nutrient issue with the yellowing tops.

What are you talking about bro? The yellow leafs? That's a marco/mobile nute shortage, it nitrogen being sucked out of older growth to feed the new growth, that if that's what you are talking about, cause I can't see anything other than marco nute def. You need to increase over all N-P-K more N to get rid of that. Them leafs will stay that color so look to old growth turning yellow still me and it's short of N. Wk 7 you should be hitting a 8-14 ppm depending on what you are happy with. For now it's just mobile nute defs I don't see any micro defs. Good luck buddy.