Contrary to the two previous installments, C-3PO had a massive role to play in the story of Episode IX by leading the team to the remnants of the Death Star in the hope of finding the Sith artifact that would help them locate Emperor Palatine. While some fans would argue that this entire plotline was a delicate MacGuffin to stretch out the last movie in the Skywalker Saga, the inclusion of Anthony Daniels’ character was one of the few points on which J.J. Abrams’ concluding entry thrived.
As it came to pass, Poe, Finn and Rey decided to wipe the droid’s memories to have him interpret the Sith runes on an ancient dagger. This gave way to one of the movie’s tear-jerking moments, but owing to the consequence-free nature of The Rise of Skywalker, R2-D2 happened to have a backup of 3PO’s memories from several days prior to that event and restored them when the group of swashbuckling heroes returned to the Resistance base.
This scene has a subtle callback to the end of Revenge of the Sith, though, when Bail Organa deletes Threepio’s memory banks to prevent him from sharing information about the last days of the Clone Wars and the fall of the Galactic Republic. This obviously cleared up all the continuity errors posed by the droid’s presence in the Original Trilogy and the fact that he doesn’t seem to recognize Darth Vader, but what if R2, who’s essentially recorded everything since The Phantom Menace, restored those deleted memories as well?
It’s certainly an interesting thought, but owing to Artoo’s general reluctance to share these chunks of information with anyone throughout multiple pieces of Star Wars canon, we wouldn’t be so sure. Though if that’s the case, Threepio is certainly in for a rude awakening if he ever decides to access his past memories again.