The real reason could literally have been anything. But the Aussies deliberately added insult to injury by saying it was too noisy without showing any data. That’s a real slap in the face to Germany’s submarine engineering.
I wonder if it had to do with Germany’s pro-Dhimmi positions. When one powerful country starts to support voluntary Muslim invasion and rape of its women, other powerful countries find ways of pushing back.
The French have their own Muslim immigration issues.