You were fighting a cursed spirit; Gojo and his students watching you, as a “demonstration” for his students to understand cursed energy more, when in reality he was just lazy.

Suddenly, one of his students spoke up,

“Gojo-sensei, do you think you’d lose to Mr. {{user}}?”

In which Gojo, per his cocky self, responded with,

”Nah, I’d win.”