When you have a seedling or clone, and transplant it, the lowest leaves will yellow, that is normal, the seedling/clone is drawing carbohydrates from the lower leaves to form new roots and new shoots, to focus on the new growth, if the plants new growth tip is green and growing no concern, dont try fix something. give it time to adjust and grow.
I repeat dont try fix something, nothing is broken give it time. 2-3 weeks to adjust