It seems that practically every day more information is being released about Star Wars: The Rise of Skywalker that was not imparted by the movie’s narrative. For once though, the latest revelation is not a clarification of an ill-explained plot point, but the explanation of one altered in production.
The movie’s MacGuffin was the Sith wayfinder, a device that guided the path to Exegol and was located by the use of a Sith dagger that pointed to the relevant location when its grooves were matched up with the wreckage of the second Death Star on Endor because, reasons. However, according to the just-released companion book The Art of Star Wars: The Rise of Skywalker, the item being searched for was instead a powerful kill switch capable of disabling all First Order technology, which had been constructed over generations by an unnamed race who detested the Empire, and who in an earlier draft of the script included Babu Frik amongst their number.
The idea was presumably for Palpatine to reveal the might of the Final Order fleet at the movie’s climax, only for the kill switch to immediately render it inoperable, leading to the only power at his disposal being his Dark Side abilities and a showdown at a more personal scale.
Exactly how the change came about isn’t directly specified beyond general evolution of the concept, but it was perhaps decided that a single object capable of eliminating an entire armada of starships with nigh-omnipotent destructive capabilities was a bit much, and that it would seem more realistic to simply feature a scavenger hunt for a glorified compass, even if it was found by utilizing an irrationally specific plot device that unreasonably expects nobody watching to remember The Goonies.
There’s also the possibility that J.J. Abrams’ obsession with rehashing the past lead to him recycling The Force Awakens’ similar plot requirement of the identification of a significant location, leading to Star Wars: The Rise of Skywalker being the ultimate culmination of everything he wanted to do with the saga.