I think that Kylian Mbappé can have a great career if he joins a good club as Messi and Neymar are not in Europe now. The rising star is likely to join the Real Madrid squad next season. I think it is best for Kylian Mbappe to join Real Madrid.
PSG currently still have the property rights to Mbappe, but with the case of the transfer market maybe Mbappe is not in 100% condition with PSG at the moment. At the moment Mbappe's mind may have been on Madrid. This problem makes Mbappe's game not optimal. I'm sure the problems at the beginning of the season had a bad effect. PSG must prepare without mainstay players and they must be able to adapt immediately. This season the coach has to start giving minutes to other players.
In my opinion, this problem has not caused Mbappe performance to decline, he is still professional now and has contributed a lot to PSG and has score the most goals at PSG, so you are wrong if you think Mbappe has not performed optimally at PSG so far.
Mbappe must develop his career not only in the French league and maybe by joining Real Madrid Mbappe will be able to win the title he wants.
As we know, since joining PSG, Mbappe has not received any titles even though Mbappe is the best player like Messi and Neymar.