Overheating for sure, the edges curling up slighlty is a big tell, the plant is unable to cool itself fast enough for demand placed upon it.
600w, 60cm away is insane amount of light for such small plants. Even at 75 I'd say your pushing it.
Have sensor read the ambient temp at canopy level raise light until the sensor has ambient 77- 80f ish or there abouts any higher.
Won't be perfect but don't prioritize intensity until you get the temps under control.
Your entire feeding schedule is based on average growth over x period. Your plant is trying to david goggins marathons on average Joe diet.