Apparently the allegations cameout during divorce proceedings when Cher's daughter law was giving testimony or evidence to a divorce court.According to the article, this "kidnapping" occurred nearly a year ago. November 2022.
For those outside the US, the source of this article, The New York Post, was once a well-respected newspaper, but is now owned by Newscorp AKA Rupert Murdoch, who, as is his habit, turned into a sensationalist rag.