In short it means if you talk too much it will backfire. I wonder why you lied to customers. Did someone told you to do so?
By the way the same counts for reviews left on sites like "Rotten tomatoes", product reviews (Amazon, Aliexpress or wherever you shop), trustpilot and so on. Read carefully and ask yourself what the review is about but also what you expect. What is bad for one can be no issue to someone else.