After 2...Nf6, 3.g3 is not so good. Do you mean 1.e4 e5 2.Nf3 *Nc6* 3.g3 from Duda vs. Carlsen, Charity Cup Final 2022 ? https://en.chessbase.com/post/charity-cup-2022-d8
Also see this thread: https://www.chess.com/forum/view/chess-openings/kia-vs-petroff
I saw a game where someone beat Carlson with this. It creates a questionable pawn structure, temporarily blocks in the fianchettoed bishop, and is a slow move in an open game. However, the bishop could become dangerous in an open game.