Paris St. Germain are a team of superstars, but as everyone knows you cannot construct a team just by superstars, and the Parisians were up against the wall as they faced Bayern Munich in Munich. And Bayern Munich are certainly also a team of superstars, but who to a much greater degree play like a team, and with tactical discipline and intelligence closed down the great potential threats posed by Messi and Mbappé.
PSG had their chances in the first half, and should have been ahead had it not been for a spectacular goalline clearance by Matthijs de Ligt. 0-0 at halftime, PSG still had hope, but Bayern Munich were far superior in the second half, with Eric Choupo-Moting bringing the Germans ahead after a clumsy mistake by Marco Verratti. And as PSG put everything forward, Serge Gnabry elegantly brought Bayern ahead 2-0 in the last minute of the match, and PSG's stars are again out.
This will surely cost Christophe Galtier his job, but the problem goes much deeper that the manager. You need to build a team!