One example of a suppressed book would be when the North American distributor of said books gets two shots to the back of the head. Another would be when its taken out of printing after a mere 3000 copies even though its author is a famous and well respected European professor. Another would be that its not translated into English even though it's by one of the most celebrated authors in the world. Another example would be when the author is thrown into prison under false murder charges because he's ruffling the wrong feathers. All true stories, to discover the books and the authors is an exercise for the reader.
If you look at the banned book list its usually because it offends Christian morality, https://en.wikipedia.org/wiki/List_of_most_commonly_challeng..., but offending social morals and offending (elements of) the power structure are very different.