Where do you get this information? Which club should feel satisfied with the price?
I still don't read any article about Real Madrid and PSG got a deal about Mbappe's transfer fees. But if it is 224 + 56 million euros, it means around 280 million euros. It is almost 300 million euros, PSG should be satisfied that Mabppe's price is still quite expensive. PSG can sign some top players with that amount of money.
I read that Mbappe's departure will not be free. He gave this statement to the club, so Mbappe must immediately sign a contract extension if he does not leave this season. So it seems that this rumor is only a release clause. PSG still continue to hope he signs a new contract perhaps with a new clause and he will not leave for free. If it is indeed agreed later, it will be a new record. I agree with you, PSG can build a team with new players even though the risk of a decline in the quality of the game can occur.
Source:
https://www.espn.com/soccer/story/_/id/37964018/psg-chief-kylian-mbappe-sign-new-deal-want-stay