It seems to me that you can't make a conclusion about the condition of the team from one friendly match.... Usually such games are not taken seriously.... Maybe for Man U this was the case... Their next game will be against Dortmund at Old Trafford.... Let's see what they can show for their fans.... If they lose again, it will mean they are bad....
Indeed, usually clubs will not play very optimally during pre-season matches or friendly matches. because they have various considerations, especially to stay away from any risk of injury. So they carry out introductions and experiments with their own players and with their opponents. But even though it's not that serious, matches like this can be used as one of the assets for evaluation to prepare for important matches in the league this season. Because after all, of course the coach can see the potential that can be further developed in this kind of competition.
Man United themselves are currently improving, of course with some of their new players, they want to optimize their performance this season. They have Onana, because she's new, maybe she's still adapting. It really needs a few more matches at least to see how they might perform in the future.