Young Sheldon season 6 delves deeper into Missy's character and reveals how The Big Bang Theory misrepresented her. While Missy had limited appearances on TBBT, her cameos established her as a character.

However, as Young Sheldon explores the Cooper family's dynamics, it becomes harder to believe that Reagan Revord's Missy would grow up to be the Missy portrayed by Laurie Metcalf. Young Sheldon showcases Missy as witty, charming, socially adept, emotionally mature, and intellectually gifted.

This contradicts the portrayal of Missy in TBBT, where she is depicted as less successful and not as smart. The improved storyline in Young Sheldon emphasizes Missy's growth and potential, overshadowing her character in TBBT. 

Overall, Young Sheldon presents a better version of Missy and challenges the perception created by TBBT.