Question: what happened to credence in fantastic beasts and where to find them?
Answer: The answer is, simply, he didn't die. Warner Bros. The movie companion book, Fantastic Beasts: The Crimes of Grindelwald: Movie Magic, explains that: "You could with justice have believed that Credence had been killed at the end of the first film. ... You can shatter the Obscurus temporarily, but the person hasn't died."