what kind of soil are you using? That is an S-ton of perlite in there, do you have any organic matter? Nitrogen? What's your nutrient schedule? The fact that they sprouted and grew fine for a week and then stopped growing implies nutrient deficiencies, they are definitely super yellow like they don't have enough nitrogen, and this could be to overwatering or not having nitrogen in the soil. Temperature and humidity are also key, if those aren't dialed in the stomata aren't opening up and the plant isn't bringing water into itself which means it's not bringing nutrients into itself either,. I just learned recently that water movement through plants isn't like a pump system, the plant isn't sucking it from the roots and pumping it up its body through some sort of mechanism. It's more like a siphon, with the opening of the stomata being the start of the siphon, but that requires a warm enough temperature for the plant to transpire. Or something like that! Haha
