Gartenlaube is German for 'arbour', or gazebo. It was the name of a popular German magazine. It maybe that the term 'Gartenlaube journalism" (translated into English as gazebo journalism) has a particular meaning to German speakers - perhaps something like the English equivalent of 'gutter press', but I don't know - you might want to post a question on the German language page to ask what particular meaning this expression has in its original language (clearly gazebo journalism means absolutely nothing in English!)

Yeah, you are right. I'm translating this book into chinese, but this sentence really bothers me. As a English-native speaker, have you ever hearded or met the expression of "gazebo journalism"?

No idea. I just googled it, and the only obvious hits are your question, and what I assume is the source book - Berlin: Imagine a City