Many moviegoers who've never read The Hunger Games series of books might be surprised by the existence of The Hunger Games: The Ballad of Songbirds & Snakes. The movie comes nearly a decade after the release of The Hunger Games: Mockingjay - Part 2, which ended the movie franchise that adapted the Suzanne Collins novels. Based on a lengthy prequel to the original books, The Ballad of Songbirds & Snakes features notable callbacks -- or rather, call forwards -- to the main series.
Source:https://www.cbr.com/songbirds-and-snakes-katniss-setup/