I Need Your Help 💚🙏

From my Point of View a Bit of CalMag, more distance to your led should fix this. As the issue started at the top of your plant, it should be one of the Both.

Looks taller than the rest... probably related to getting more light -- also relegated to the top portiosn of the plant that look taller than the plants on each side. damage directly along the veins also hints at a "too-wet" root zone or just something wrong in the root zone, maybe pH? Review orthodox watering habits below and make sure you are doing something similar. Give the taller plant a slightly higher concentration of fertilzier and correct any improper watering habits.. Go slowly adding more for that 1 plant. If the plant reverses course it's now getting a surplus, you may need to dial it down slightly in the future after any chlorosis fills back in with a proper green... but it'll still settle on something a little higher than the other plants. ----------------------- watering 1) fully saturate - 10% runoff if soilless, or minimal runoff in soil to ensure it's wet all they way down. 2) wait for appropriate dryback -- weight loss or depth of dryness are two good triggers. You do not choose the volume of water to give. You give what is required to accomplish step 1. If you are consistent about your trigger in step 2, you will learn the volume necessary in hindsight for better planning ability. I prefer weight loss as my trigger. Never partially water. Never spritze the surface etc... These are terrible habits that may not lead to a problem each time, but will eventually cause something that was 100% avoidable otherwise.

Yeah I agree.. more feed for this 1 with calmag

oh one last thing feed as you normally would maybe a smidgen more but throw in some extra calmag as well

don't worry drop in some growers recharge and lower the pH to 6.5 looks like she stole your nitrogen for her stretch phase so I would lower the pH and keep feeding as she will resolve this later into flower she's the biggest and may have just needed a little more but overall looks healthy