RAF and US 8th Air Force bombing along with perhaps some Russian artillery near the end of the war caused a great deal of destruction. Postwar, the division of Berlin into occupation zones resulted in the border of the Russian Zone crossing through the plaza. The 1961-1989 Berlin Wall followed that trace. The result was the obliteration of Potsdamer Platz as it had been prewar.
Following Germany's reunification, the neighborhood has been rebuilt in Modernist form. I was there in 2018 and found it an ugly, sterile place.