My plant a few days ago looked sad and people said...

Looks like the soil you are using is too hot for seedlings. There's not much you can do just keep environment right and I'm sure as it gets bigger it will balance out. pH should be about 6.5

You don't feed seedlings. They feed themselves the first 2 weeks. They don't like saturated soil either. They need to breath. Simply stopping watering isn't going to achieve a miraculous turn around. What you need to do is increase the heat and drop the humidity in your environment to encourage faster transpiration and evaporation. A gentle breeze blowing periodically back and forth across the soil surface will also help. If it lives, it won't rebound until it's able to breath properly at the root level. Over watering causes suffocation in the root zone. With no roots to absorb the moisture, the water is just gonna sit in that soil and kill your seedling unless you help it along by changing the environment to get back control.

Ich baue auch organisch an und kann dir sagen, dass die Erde zu heiß für die kleine Dame ist. Die Pflanze hat eindeutig einen N-Tox. Nimm sie da schleunigst raus und lasse sie erst einmal Wurzeln in Light-Mix bilden. Du willst nicht, dass die Pflanze in dieser Größe und mit diesem Alter in Living-Soil steht. Ziehe deine Pflanzen IMMER die ersten 14 Tage in Light-Mix an und lass sie Wurzeln bilden. Erst wenn die Basis der Pflanze stark genug ist, darf sie in das organische Substrat. Ich hoffe ich konnte dir weiterhelfen Terp 😎

If it's nitrogen poisoning, it will get worse if you water too low. It must be clearly ensured that the plant is not overwatered. Check the moisture at the bottom of the pot with thin wooden sticks. Carefully insert it around the edge, all the way to the bottom of the pot, wait 10 minutes and then see if the wooden stick near the bottom is moist. If it's not moist too much, you can water it. On tge stick you xan see also, how deep in soil moisture starts, and where dryness ends. Watering reduces nitrogen poisoning because it is no longer as concentrated. Under no circumstances should you fertilize! So it could be, that the plant was overwatered first, Leaves were hanging down, then it dried, and therefore nitrogen toxicity increased, - leaves become a deep green.

I am using organic roots in organic soil, and the strain is Ak-47 by serious seeds. My grow tent is at 78 at 70% humidity.

This very dark green indicates nitrogen toxicity rather than overwatering. Without knowing more about your crop, it's hard to say what's causing it or how to counteract it.

What substrate are you in Coco or soil ?.