It’s on the banner used by Goebbels for his “Totaler Krieg” speech. Possibly it was just custom for the banner, but at the very least the letters mostly look like something I recognize but can’t name. The O and Ü look a bit wider than what I’m probably thinking of.
Here’s a photo from the speech:
(Link shortened because of brackets in the URL. It’s from the German government archives.)
Considering that Hermann Zapf didn’t design Optima until the 50s, I’d say this was a precursor to it. It certainly looks like Zapf’s humanist sans-serif work.