Something I've seen often in TV shows is that Germans, around 1943 and 1944, speak openly about the war being a lost cause. Was this really something that was known? As far as I know the press was controlled tightly, and would have made it difficult to get any real information.
While there is more to be said on the subject, the following answers might be of interest to you:
u/vonadler addresses views of German leadership in At what point in WW II did the German military realize the war could not be won anymore and did how did they try to act on it?
and u/kieslowskifan addresses changes in German propaganda in How did propaganda change in nazi Germany after Stalingrad and Normandy?