Mbappe is not the only player that has missed a crucial penalty even the best players do Ronaldo and Messi. When a game doesn't want to go in your favour there's nothing you can do about it, even if you used all the best player in the pitch, and I think that was the situation with Real Madrid in that encounter with Bilbao last night that they lost the game. Any player can miss penalty and I doubt if Mbappe wouldn't have wanted to score the penalty for their team to win.
It doesn't really matter to anyone who fails to execute a penalty but what disappoints everyone is that the penalty was very important for Real Madrid in that match if Mbappe didn't fail he would have saved his team from defeat but because of that failure that caused his club to lose, I don't think Mbappe can be trusted to take penalties because the pattern he uses can be read by the goalkeeper it's better to use Rodrygo if Vinicius is not there.
Once it fails maybe unlucky for a player, but in fact he has failed a few times before in scoring goals through penalties, so I think Ancelotti needs to rethink Mbappe role as a penalty kicker at the moment, the fans disappointment has been huge towards Mbappe, especially since he is indeed unreliable when Madrid have to play in a crucial match so far, regardless from the penalty failure, so far he has not been able to show impressive performance in Madrid as he ever showed at PSG, but strangely Ancelotti seems to have like no other choice but to continue playing Mbappe although he actually has many other options in his squad.