Andre Onana is just under pressure, this one of the reasons he's not exploring and succeeding in Old Trafford. When he was in his previous clubs, nobody expected much from him because there have been divided attention to the players because the goalie is only present to do his best keeping saves but in Old Trafford, they expects every goalie to be at their best, besides he was fulfilling the shoes of David De Gea who everyone thought to be 3x times better but it reverse is the case.
Manchester United will struggle this season base on the unpredictable rigid foundation of Ruben Amorim. How can a manager have competent players and new signings and still been unable to accomplish top results. Anyways, let's give him time just like we gave Erik Ten Hag but ended up doing nothing for the club.
Another reason Onana seems to be under pressure is cause he's trying not just live up to the standard De Gea set, he also wants to surpass it and prove to the club that the same thing he did at Ajax and Inter ( which was to help them carry trophies) he could replicate at Man UTD but the mistake he made was thinking that he could do that alone. Onana is a very good goalkeeper no doubt but the fact that the defense is not strong, there's only so much weight he can carry. In the early period of his time at Old Trafford, he was covering the loose ends for the club but overtime, the pressure became too much for him. I feel that he should take some time to rest because at the moment, United are yet to find their footing, so it's either he doesn't start some games and take sometime to rest or he looks for another club where the expectations aren't much.