Could be a lot of things. Sometimes clones turn a little yellow on the leaves it had when it was cloned. The plant was just relocating nutrients and sucking the leaves dry. Or if your feeding it already you may have burnt it. Looks like organic soil to me. Is it? And have you been feeding yet?
I have not been feeding it yet because the soil I have has composted forest humus, sphagum peat moss, Pacific northwest sea going emulsion, crab meal, shrimp meal, earthworm castings, Sandy loam, perlite, fossilized bat guano, granite dust, Norwegian kelp meal, and oyster shell, and it is ph adjusted already. I water my plant every 3 days in a 5 gallon bucket and also have some horticultural molasses but haven't used it yet