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Yes, they look weak. They look like they have no enough light and no nutrients at all besides already contained in soil... You could grow them on window sill and just water with plain tap water - and you just might get a better result 😇

A lot of this comes down to genetics. Sometimes no matter what you do the genetics will be bad. In this case I think you’re running into both genetic issues and poor husbandry on your part. If you are indeed watering daily you need to stop NOW. Water as needed, likely in your case every 3-4 days. When you water, about 10-20% should run out the bottom of the pot. This prevents the build up of excess nutrients in your soil. Your light should be run to whatever setting gives you roughly 750-900 PPFD at the top of your plants. You can download a PPFD app to figure this out. Lights on autoflowers should be 18 on and 6 off. Your plant genetics looks to be a very heavy leaning Sativa. Which means your plant will be tall and lanky and there is nothing you can really do about it. I hope this helps.

you dont water soil daily, it has to have wet/dry cycle. if light is really 500w, then only weak genetics and bad watering could make them so lanky and stretched, root system too weak, so plants are weak. soil and coco mix is stupidity in my personal view. by feed you almost have nitrogen toxicity, so its not a lack of food.

Not enough fresh nutrients at the root tips.

Check your run of ph (should not exceed 6,5) and adjust it if needed. When you've adjusted pH and you've created the right environment for her roots, give her normal npk because she def needs N (yellowing) and K(purple color on leaves ). Always check pH and ec of your irrigation water

I don’t know my arse from a humidifier, but since it looks like it’s just the top leaves, it may be that your light is too close to the top of the plant. Looks like light stress

Some of that may be temp/genneics erlatd (the purple or red hues). If temps hit 66-68F and below, you get fall colors in plants.. some genetics display it regardless, too. But, definitely have some nutrient issues going on too. some interveinal chlorosis down below? can't really see.. looks a bit pale, but that also could be an illusion of grow lights + photography. need more info / better pics of damage.

Had exactly the same symptoms on this plant after overnuting

likely overfed and to much light need more downtime. 20/4 is a bit much. I like to keep it max at 18/6 for autos. Should try and calculate your DLI your giving them at 20/4 Don't want anything over 35-40 for most plants and environments. Some can take more but you need to add in extra co2 and have other aspects dialed in. I don't think by the looks of it your hitting that 40 mark given the stretch of your plants but still should try and check it to know. Good Luck!