Casemiro's game often endangers his own club, it is very unfortunate that the red card really put Manchester United in danger, this defeat was really surprised them and put United in the bottom standings so it will start to raise doubts that they can survive in the Champions League. because losing in a home match is a big loss.
A team from the English Premier League also had unpleasant results because Arsenal lost to Lens even though the away team managed to control the match Lens managed to take advantage of better opportunities.
What Casemiro made was due to Onana's own mistake for passing to the opponent while Casemiro behind him tried to defend by making a tackle, as a result it became a penalty even though the Galatasaray player failed to execute it.
After that they lost their balance in defense to catch Man United defenders off guard, this is even more dilapidated into the Man United squad, Onana with an expensive goalkeeper has a lot of goals if I'm not mistaken after he joined 18 goals into his goal.
Man United's situation in Group A is getting worse, I'm not sure they will make it through if they see this poor performance, Erik Ten Hag has not been able to evaluate as a whole.