Nute burn !? Or def

Keep your ph at about 5.8 to 5.9 for vegging as well. 👍

Okay, you are in Hydro I see. I have used the blue planet elite nutrition for a few years. You need some cal mag. Also only the root tips should be in the solution. Don't be scared to trim the roots for pruning. This will provide a healthy root base allowing for more solution, and a healthier plant. I have 2 autos going into flowering soon I am doing dwc with. Feel free to look at each week. I take pics of before and after root pruning each week. I usually have to trim the roots every 3 to 4 days.

could alwys be an oddball too... like an equivalent to diabetic or something.

check roots for discoloration or slime... double check pH if all good, some sort of imbalance in the feed. 400ppm is a light mix. i'm feeding 600-650 from first week and amping up to 700ish. so if it's a tox, that's crazy. need more info. if blue planet breks down ppms at various concentrtions that would be useful or use a calculator at.. (randomly in my clipboard for paste, lol) - https://manicbotanix.com/calculators/ppm-in-solution-calc.php type in % fromlabels, tabulte it all.. know how it goes up and down from there, reference a leaf chart as you see things.. before long you'll know an upper andlower range that is safe relative to your garden's environment and amount of light provided.

My nutrients can be old

It never was out of rage always 5.6-5.9

I'm guessing pH out of range caused it What's the pH you adjust to? Has it ever been outside the range of 5.5 and 6.5

Also she have sister same age and she’s doing great