During the battle with Palpatine
One of the biggest gripes about The Rise of Skywalker is the final battle with Palpatine. When Rey and Ben are battling Palpatine, no past Jedi show up to help when many were expecting them to. After Ben is launched away by Palpatine, and Rey lays on the floor all but defeated, she does reach out in the Force and hears inspiration from past Jedi.
That was great, but it would’ve been so much better to see them in ghost form. Anakin especially should’ve been seen here. He, along with the rest of the Jedi, could’ve been shown holding out their hands, using the Force to push Palpatine’s lightning back at him. To defeat the greatest Sith who ever lived, it should’ve taken all the major Jedi we’ve seen throughout the saga to do so. Luke, Leia, Obi-Wan, Qui-Gon, Yoda, and especially Anakin all should’ve been seen here and not just heard. Anakin was the chosen one and destroyed Palpatine the first time, and should’ve had a bigger part of him being beaten for good.
This was the biggest missed opportunity in the Skywalker finale and one that we can only hope gets corrected in a future special edition version of the film.