...
But yes, I don't know in how far ten Hag is involved in transfer decisions and whether he has a lot to say in the club when it comes to player transfers, but there have been some questionable decisions in the recent past.
I don't think he is entirely to blame for Manchester United's poor form. In the past they have spent millions of dollars on players like Jadon Sancho, Harry Maguire and Anthony Martial and they have never benefited from them. So, there is a long history of bad and wrong transfer policy at Manchester United. They are like Chelsea, but not as bad as Chelsea.

I don't think Erik ten Hag has a squad that can compete with his rivals. Manchester United need a lot of transfers and they have almost no chance of winning the Champions League.
Ten Hag was able to manage the Manchester United squad well in the first season of his career there, Manchester United performed better under his guidance and ultimately managed to qualify for the Champions League this season. At that time he inherited the squad left by the previous coach, although there were several additional players during the season, but Manchester United's performance was much better than this season.
The current Manchester United squad is predominantly filled with players appointed directly by Ten Hag, but strangely he seems to have lost direction in managing Manchester United. I think Manchester United poor performance is not due to a bad transfer policy, but because Ten Hag ability is starting to decline in managing Manchester United.