As of that time, Stray Kids is a K-pop group known for its unique members, each with their own personalities and characteristics. However, I don't have access to private information, so I can't determine which member is the most introverted or their current personalities beyond what was publicly known .
K-pop groups can often display different sides of themselves in public and private settings, and individual personalities can also change over time. For the most up-to-date and accurate information, I recommend checking recent interviews, articles, or official statements about Stray Kids and its members.