Star Wars: The Rise of Skywalker saw the return of Ian McDiarmid's Emperor Palpatine, but the Star Wars franchise is now close to retconing how this was achieved. Although the movie didn't go into detail on how Palpatine managed to survive his death in Return of the Jedi, the characters did provide a brief explanation for how he could've come back. However, thanks to the Star Wars TV shows, most notably The Mandalorian, it's clear that Star Wars is setting up a massive retcon for how Palpatine returned in The Rise of Skywalker. This will tie various Star Wars projects together and improve The Rise of Skywalker's Palpatine explanation, too.

https://screenrant.com/star-wars-palpatine-return-retcon-the-mandalorian/