Barcelona has very young players who don't have the confidence and boldness to play with one man down and win the match.
Barcelona has a good player resource from La Massia but youth player quality from it can be good or bad, they can not grow up every player to be Messi, Xavi, Iniesta and after their golden era years ago, they did not get good youth players from La Massia. Until recently they had Lamine Yamal who is very promising to be a next super star player, to compete with Mbappe and Haaland for Ballon d'Or in future.
About mentality of young players, they are weak and very few youth players can play with super high confidence like Yamal. In order to help youth players play well, even they are talented, Barcelona must combine youth players to their squad with experienced players very cleverly. It's a way to grow up youth players, support and defend them against pressure.
I think the coach should always prepare them for a man down mindset so that they can know how to play the match and draw it than losing it because it is possible.
It's exactly one of responsibility of a head coach because if youth players are used in a wrong way, pressure and expectation, then injuries will destroy their career very quickly.