This was only natural; after all, everyone here was determined to give their best shot at debuting. For some, this might be their last chance, making the pressure even greater. Feeling nervous during the first mission was understandable, especially when having to follow Taeyang's performance. It would be difficult for anyone to perform comfortably under those circumstances.
Thankfully, the fourth contestant performed much better compared to the first two. While he struggled with the a cappella section, he managed to complete his song once the backing track started—an improvement over the previous two contestants, who didn't finish at all.