From what i can see the plants looking alright, LEDs can play funny tricks with lights, they can also be notorious for light burn as there are so many varieties. Personally if there is damage it doesnt appear too severe yet. Perhaps lower lights to 18 hours for more rest. Otherwise examine other potential excesses or deficiencies. From the photos your medium looks fairly dry...i dont know if this is a common occurance or photos just taken before watering. I had a plant suffer from chronic irregular watering practices and it caused a variety of issues discoloration, leaf damage etc.
I hope we can see some photos soon without the led so we can all get a bigger idea of the possibilities.
Happy growing and keep up the good work, growing cannabis can certainly have its hard frustrating moments. โ๏ธ