How to grow seedling in tent

I think you're burning your seedlings. Light burn and heat stress. That light is way too big, too hot, too powerful and way too close to your seedlings. I only use 1 or 2 50watt house-plant LED lights (white full spectrum) for my seedlings in a tent that size. You can put a cool light like that quite close without the plants burning. But their growth will stunt badly if they're stressed by too much light and heat. The light I use in my seed tent is just a generic one but it doesn't have an inbuilt timer. As long as you search for a light that matches the specs I gave you on Amazon and make sure it has no timer (because it's worse than useless) and use a timer plug, that's all you need. They're not expensive if you look for a two-headed lamp both with 50watt bulbs on the end with snake necks and dual switches. They'll recover once you stop burning them.