In the years and stories following 2019’s Star Wars: The Rise of Skywalker, the Star Wars franchise has worked to explain how Emperor Palpatine‘s resurrection came to be with Project Necromancer. First identified in The Mandalorian season 3, Project Necromancer has since been fleshed out in Star Wars: The Bad Batch season 3, identifying Doctor Royce Hemlock as the lead scientist responsible for figuring out how Palpatine could make his return from the dead via cloning. The timeline of this project, however, has remained in flux – but its starting point has at last been identified.
https://screenrant.com/star-wars-palpatine-project-necromancer-experiments-beginning/