So at the beginning of the story when Gojo-sensei said that Yuji didn't have a curse technique it was due his nature as a vessel, which essentially allows him to gain ANY and EVERY cursed technique/object he swallows instead(?) He doesn't have his own CT but in its place he can have multiple ones, ranging from weak to ones as strong as Sukuna's and Choso's.
I remember sensei saying that over time Yuji could use Sukuna's techniques, but I'm guessing he was referring to a time where Yuji would have perfected his control of cursed energy (something he was just learning).
The way my heart warmed up with Choso's comeback and his caring for our baby Yuji. Also, I believe Yuji's sudden relapse is not due to his RCT having failed to heal his wounds properly as he thinks. You see how they keep repeating the similarities between Yuji and Sukuna's soul and all that? It looks as if the pain of the injury Sukuna sustained by Maki's Slit Soul Katana is reflecting in Yuji. I'm afraid that if he manages to heal himself with Choso's guidance that it will involve indirectly healing Sukuna, speeding up his RCT that isn't working at full capacity thanks to the sword.
So... my man Yuji is about to get caught in the middle of those domain expansions. Sukuna really got distracted with Yuta's apparition, but I don't think Yuji's gonna keep still anymore. He was about to crush Sukuna's heart and has already made so much damage to the barrier between his and Megumi's soul. I think Sukuna's end is approaching...