He seemed to be in a hurry last year when he wanted to bring in several players. especially when the decision to take a new goalkeeper was quite controversial.
I don’t really know maybe Ten Hag was having some personal problem with De Gea, I was surprise just to see him send De Gea way from the club even as we know that De Gea wanted to stay in the club, Ten Hag should have to allowed De Gea stay in the club, leaving him as a second goalkeeper won’t really be bad, De Gea made some mistakes last season, but he still performed well in most matches, De Gea is just better than their current goal keeper which Ten Hag signed, if De Gea haven’t left the club, then he will be able to replace him with Onana since his performance is really impressive, he is performing below people’s expectation, the hype was just too much when he was about to be signed.
It wouldn't be the first time that ten Hag has a problem with a player

This guy has problems with players all the time and that's why he is a big burden to the club. I am not sure why he is still around since he is literally destroying Manchester United slowly but surely. No way they are going to be around in the Champions League next season. They also missed the Europa League and it couldn't get worse than that. They are not playing against the relegation zone, sure, but this has nothing to do with Manchester United. They are not even average anymore and every time I thought they might turn things around, they failed even harder. The last game in the Champions League was proof enough.