For me the problem is not squad depth but the manager is not able to make the most of the quality of the players he has. Arsenal, Chelsea and Liverpool also don't have much better squad depth but their performance this season has been much better.
Manchester United have fulfilled all Ten Hak's wishes in recruiting new players but he has not been able to deliver good results for the team.
The problem is more directed at the Manchester United coach himself because he really is not able to provide such maximum tactics to all the players he has recruited in the last two seasons. So what the Manchester United team management must do now is look for a new coach in the current season and end their cooperation with Ten Hag for the good of the team in the future. Because it would be very unfortunate if a team as big as Manchester United became worse again when still handled by Ten Hag in the next season.