Pre-season games usually don't have any motivation for the top clubs to win the game. Yes, I agree that in this match both teams gave one hundred percent of their abilities. But this is not the first time a top team from the English league has lost to a mediocre team. I think Manchester United really made this a game to test a lot of different tactics. Rosenborg scored a goal late in the game so I think both teams played very well. But a defeat is still a defeat and Ten Hag also said that this was not the performance United should have.
If Ten Hag has started to realize this at Manchester United, of course he himself knows what he actually has to do before the season actually starts. Because in terms of time, it is still possible for Manchester United to make more evaluations and better strategies to be able to start next season as well as possible. And apart from that, losing in the pre-season match also didn't harm Manchester United even though it could make the mediocre team feel happy and enthusiastic enough to start next season in the Premier League.