For Mbappe, I also don't know for sure about his new contract extension with PSG, I think this is very secretive by PSG management so that it doesn't become a media conversation anymore.
I presume Mbappe clan is in discussion with Real Madrid in addition to PSG to find the suitable contract for him. In any way Mbappe will not accept a contract that limit his possibilities to move whenever he wants.
Mbappe will try to avoid being a new Lukaku and PSG will avoid looking fool this year too.