Philosopher Nancy Fraser talks about cancellation of a lecture at the University of Cologne...

...because she signed the "Philosophers for Palestine" letter noted in the fall.   Academic freedom (more precisely, freedom in research and teaching) enjoys constitutional status in Germany, although I'm not sure if it encompasses decisions by academics to invite certain scholars to give lecture series (it would in the U.S.).  Of course, Germany has a very different free speech regime than the U.S. (all democracies do, by the way), one that includes prohibitions on certain kinds of hate speech and in which human dignity is the supreme constitutional value.  It seems to me dubious that that letter would run afoul of those limitations, but I am not expert on German constitutional law.