The last criticism of Nazism was a very milquetoast 1934 speech by a Nazi, Franz von Papen, who though supporting Adolf Hitler detracted in some (seemingly) lesser ways—decrying the fanaticism of Hitler's personality cult. He was severely punished for it.

https://en.wikipedia.org/wiki/Marburg_speech ("...said to be the last speech made publicly, and on a high level, in Germany against National Socialism...")

An ironic tombstone for freedom of speech:

"They will bear them and follow the Führer with unwavering loyalty, if they are allowed to have their part in the planning and in the work, if every word of criticism is not taken for ill will, and if despairing patriots are not branded as enemies of the state."

The last high level public criticism within Germany. Nazis of course still got criticism and satire elsewhere. Hitler Has Only Got One Ball and the like leading up to their defeat and Hitler shooting himself in a bunker.