Sick really sick

Hard to say with the information given but if that light is a 1000w it’s way too close to a plant of that size. It should be half that wattage or twice as far away. Based on the crispy sound your leaves were making in the video they are getting baked and not in the good way haha. I’d raise the light and watch the new growth I sure it will recover just fine when you do so

no, not sick little bit of nitrogen nutrient problem, but only on older leaves. older leaves won't recover your problem is solved already if this happens to your new leaves, add some nutrients (fertilizer) Good luck

From the videos, I don't think there's anything wrong. If how you say the leaves are turning light green, then after 6 weeks your soil is more likely a little depleted of nutrients, in particular Nitrogen, you probably are feeding too little. Are you measuring your feeding EC or PPM?

It looks like lack of nitrogen. Do you ph your water when you feed your plants? A lot of problems occur due to the ph being off.