You might be confusing it with another film or have heard about a rumor. There was some controversy surrounding the film's marketing, which used real-life crimes for inspiration, leading to criticism. However, the film itself was released and is available on various streaming platforms.
It's possible you've heard about the "Poughkeepsie Tapes" in connection with the real-life crimes that inspired the film. The film itself is a fictionalized account and shouldn't be mistaken for a documentary.