What happen of my girl

75% 400w MH, about 20000 lux, The leaves sag on both sides, and the surface is uneven, andother put at same place is find, it look like light burn?how I can fix it now?pls help

Looks like overwatering to me. I'm not seeing any burn. Just let the soil dry out a bit.

5-7k lux for seedlings

Dry /wet cycles man. Don't over water

I also think watering was your issue. I think you should correct your watering and focus your attn on your light height. Stretching is about to be your problem.

Over watering or high concentration of nitrogen plus over watering

Get the light closer & when you replant bury the stem down to the first set of leaves

Ok, many thanks to everybody

Yeah add more dirt move light closer. If your soil is wet raise the temp of your room she will perk up. make sure you have a fan blowing air on her softly and gently.