Looks like the plant is starving for fertilizer and cal mag. Even the same strain from the same breeder can have different needs between plants. I suggest a 1/2 strength feeding with cal mag.
Also, what are you ph’ing the water to? For soil it should be 6.4 to 6.6 or 6.7. If you’re not ph’ing that could be the issue as well.
Finally, how close are your lights. I have the MH TSL2000. Your light should be at least 18 to 20 inches above the plant.