I'm using a Migro 100 COB LED (1.9 to 2.1μmo...

Hey there Anonnabis, actually that leaf curling is probably an indication of root problems due to the fact that the soil medium is too hot, meaning the microbial life in there is all over the place. This is creating imbalance at the root zone which is already weakened by the temperatures, leading to early root problems. I dont know what you're using as pH down, but plants in soil like anything from 6 to 6.5 might be best to raise it a little especially at the seedling stage. Water with colder water like at 17°C or something, see if you can get the soil temperature down. To fix the problem roots you can use enzyme or other additives and chelation agents such as amino acids or humic and fluvic acids, these break down the unhealthy roots and promote healthy roots. I would put your light way down by the way, it wasnt causing problems actually and a too long lamp to plant distance will cause an unwanted stretch in the seedling. Hope this helps ! 🚀