Manchester United really need some of the best players for their team next season in order to be even stronger in all matches next season, but with an offer of that size I think it makes sense for Barcelona to turn it down. Because basically Barcelona is in need of a lot of funds to build a better team next season even though Barcelona are currently in a financial crisis. But it would also be very good if Manchester United were willing to make a second offer that was slightly higher than the first to get De Jong.
It doesn't seem appropriate to compare countries and clubs. But you have to know Rangnik led Austria to a 3-0 win over Croatia. Remember this is Rangnick's first debut. So if you look at this of course I'm sure here is not Rangnick who makes Man United bad, but I think there are mental and motivational problems from the Man United players. That's what Rangnick hasn't been able to overcome at Man United. So at the moment Ten Hag's decision to sell some players and let them go is the best move for Man United's progress. But I'm also not sure next season Man United will be good and stable.