Mount himself didn't seem to hide the fact that he wanted to leave because of Chelsea's failure this season. He's a good player, but it's hard to see that in Chelsea. The whole team played horribly under Potter and then horribly under Lampard. It was no longer a question of a winning spirit, it was just a matter of staying in the Premier League and not getting relegated. So it is logical that Mount did not want to re-sign with Chelsea and decided to move to a club with championship ambitions, Manchester United.
I was quite surprised by the number Mason Mount was jersey. He's a young player, he has good ability but still under Ronaldo before he went to Real Madrid. Of course Ten Hag has a reason why Mount was given that number, but no news has been circulated yet. Hopefully he is able to give his best game and does not fail to develop like the previous players who wore number 7. If I'm not mistaken, Man United spent 55 million pounds with a bonus of 5 million pounds if Mount can succeed in winning the EPL and UCL.