Am I right in saying that its actually only say just under 2 weeks from the 1st leafs showing if I'm counting from the day I potted them lol neava thought it would be so complicated lolI’m not much of a soil grower so I can’t comment with as much experience as other but if I was too guess I’d say the issue is over fertilisation or watering. If that seedling is three weeks then the best course of action would be too pull it and start again I’m afraid.