Star Wars made the bold decision to bring back Emperor Palpatine in the final installment of the Skywalker saga, Star Wars: Episode IX – The Rise of Skywalker – but the idea may have been hinted at years earlier. Palpatine's return from the dead was a controversial creative choice, and its ramifications on the plot of not only the sequel Star Wars trilogy, but also the Skywalker saga as a whole have been huge. Some viewers enjoyed his reappearance, as it was brought upon by a Revenge of the Sith reference, but others detest it, claiming it came out of nowhere with no previous setup.

https://screenrant.com/star-wars-palpatine-cloning-bloodline-novel-rise-of-skywalker/