Between his love for his family and his rise to evil, Anakin Skywalker (aka Darth Vader) flaunts one of the richest stories of any antihero in Star Wars and, more broadly, pop culture. The Rise of Skywalker has arrived, and Hayden Christensen is officially back, baby. While his role is minor, the fallen Jedi definitely returns to cap off the sequel trilogy.
With Palpatine's comeback, it only makes sense that Anakin will reappear to complete a full-circle narrative with the prequel and original trilogies in mind. But his part may not be as significant as you may have guessed. Anakin returns as a Force ghost in The Rise of Skywalker as he did in Return of the Jedi. Instead of speaking to Ben Solo and guiding his wayward grandson back to the light side of the Force, he reaches out to young Rey in one of Episode IX's concluding moments.
When Rey confronts Palpatine, the evil Emperor drains her and Ben Solo of their Force dyad energy, using it to rejuvenate himself. Extremely weakened, Rey draws upon the strength of the Jedi before her, reaching out through the Force. She hears a cacophony of voices, including those of Obi-Wan Kenobi and Luke Skywalker. Of all the Jedi, Anakin imparts the most wisdom - and by most, we mean around four lines.
Anakin tells Rey to bring back the balance to the Force as he did. In Return of the Jedi, he throws the Emperor down a reactor shaft and is electrocuted in the process, sacrificing his life to save Luke. By killing Palpatine, the fallen Jedi restores the balance of the Force. Back to Episode IX, Anakin also reminds Rey that the Force surrounds her and that she should allow it to lift her.
So, yes, Anakin's return isn't a seminal plot point. Still, we're glad to have him back in any capacity, even if that means mere seconds of his voice for fan service.