Since he was at PSG, he was the best player at the club, but since coming to Real Madrid his confidence has faded, he seems like a player who is still learning to play football. His penalty misses against Liverpool and Athletic Club were a rare occurrence, he missed two penalties in the space of a week. Mbappe has also failed to convert 13 big chances in La Liga this season, no other player has failed more than 10 attempts, his mentality is really down because since he was brought in he has not been able to meet the club's expectations, especially since he is also experiencing personal problems that have an impact on him psychologically such as not being called up to his country's national team and the conflict between him and PSG.
I think mbappe is that kind of player thats good when he is at a particular league side, he is making me to believe that Spanish laliga style of football doesn't fit him, he is struggling to fit into their style, I don't know if I will say he hasn't adapted to Real Madrid pattern of play may be due to the reason that this is his first season there, I don't even know what to attribute this kind lapses to, though we keep watching to see if he will change but it's becoming very serious, though I don't blame him very much for faling to score a penalty for consecutively 2 times like I said earlier in some post of mine, scoring penalty is a luck but more is expected from mbappe as a star and his not giving Realmadrid what they want from him presently, mbappe has failed in different angles, i think Realmadrid might be having a rethink soon if this kind of underperformance of his persist, having problems with PSG and not being invited by his nation as you said shouldn't make him lack concentration in a team that he has always wanted to play in, his country side invitation problem can be fixed but that of his former club i wouldnt know but I think is time for him to concentrate on his career because as it stands his carreer may be threatened if he continue this way.