Unknown? What do you mean?
Mbappe issues already spread anytime since the previous season. Although Real Madrid failed to sign him in the previous transfer window, it doesn't mean that Mbappe has no chance to move to Real Madrid. Moreover, Real Madrid still prioritizes Mbappe as their main target, meanwhile Mbappe still dreams to join Real Madrid. So, public (all people) must understand that Real Madrid has a good chance to sign him.
Mbappe mustn't renew his contract with PSG. If he extends his contract, he may play forever with PSG. I actually don't understand why PSG too relies on Mbappe for their attacking line. I think PSG will be better to sell him and get huge funds, then PSG can buy another top striker for their attacking line. PSG also can lower the salary for the new striker, it is probably lower that Mbappe's salary.
Indeed Real Madrid still prioritize for signing Kylian Mbappe or not but they have bad experienced when trying sign him last several season when his contract expiring and one more step closer for reaching agreement deal but Mbbape accept new offer from PSG. I don't think Real Madrid will prioritize with players have make them get disappointed last two season and try to sign him although Madrid attacking line right now more solid.
Current salary from Mbappe with PSG is 72 million EUR per season and its huge amount will get potential up drastically for renewing contract with PSG or other interested team will give higher offer payment salary above 72 million EUR. Left 27 days before deadline of winter transfer window close still not have any progress with Kylian Mbappe will extend his contract or acceptable new offer from other teams but Real Madrid will not sign any player yet in winter transfer window.