Hmm I wonder if " is declining because of Megumi " is bc Megumi is doing something OR again Sukuna overestimated how useful that swap would be, that would go along whit my theory of Kenjaku having designed Yuji specifically for Sukuna, to both contain him and make him use his powers to the fullest, like yeah you get a new CT but as a vessel Megumi has more limitations than Yuji