Did way too little to progress and circulate the ball.
When general play is as bad as it was in the first half, you have to look critically at the midfield. For Gavi as usually there was no structure to what he did. For Bernal there was a lot of standing around and only receiving the ball when incidentally space opened up around him. Made it very easy for the opponent to stifle our game. As a midfielder you have to do more than occasionally play a nice pass.
Then Pedri came on and did everything. Made himself available, carried the ball, played it off, made the game flow. Then Bernal looked less exposed but not because he improved himself, was just being babysat.