They are pretending TLJ, and ROTJ didn’t happen? I guess that was the best option they had. Palpatine dies, Vader redeems himself, end of character arc.
Going 100% fan service.
He’s a Sith... he knows how to come back from the dead. But apparently it took him some time to pull that off.
In the otherwise crappy prequels, palpatine did tell young anakin skywalker that together they can discover how to cheat death. I always though that his presence was still alive kinda like Sauron in the Lord of the Rings. Still Disney destroyed the SW franchise with crappy story lines that don’t make sense with canon SW knowledge and they have a lust of killing off all of the favorite characters as soon as possible. I can’t understand how Rey hasn’t been taught by anyone even Luke (he really didn’t) and can do advance JEDI moves