Star Wars: The Clone Wars season 7 made Star Wars: Revenge of the Sith's opening battle all about Ahsoka Tano. Anakin Skywalker only became a padawan because Qui-Gon Jinn vowed to personally train him to be a Jedi, and Qui-Gon could have been the perfect mentor for Anakin, showing him how to be a Jedi apart from the Jedi Council and question the Jedi dogma without abandoning it entirely. Unfortunately, he was killed by Palpatine's Sith apprentice, Darth Maul, isolating Anakin from the one Jedi he needed most. Right before his fall to the dark side, Palpatine separated Anakin from his own apprentice, Ahsoka Tano when she was the one Jedi who could have saved him.
At the end of season 5 of The Clone Wars, Ahsoka was falsely accused of a crime and stripped of her rank and title by the Jedi Council and handed over to a military court to be tried for treason, with Palpatine himself acting as judge over the trial. Anakin presented evidence exonerating her at the last second before Palpatine found her guilty, but when she was invited to return to the Jedi, she rejected the offer, having lost faith in them after her experience, also fueling Anakin's own existing distrust of the Jedi Council.
Ahsoka went off on her own and learned more about the galaxy and her place in it, coming to a more mature understanding of her relationship to the Force and the Jedi, making her exactly the person Anakin needed to confide in during his last days as a Jedi, and they were even reunited in The Clone Wars season 7 at just the right time for her to provide this support, but Palpatine's "capture" by the separatists conveniently stopped that from happening as Anakin and Obi-Wan rush off to rescue him (as depicted in the opening scene of Star Wars: Revenge of the Sith).
Ahsoka approached Anakin and Obi-Wan with Bo-Katan Kryze to request Republic support to liberate Mandalore from Darth Maul. Obi-Wan was concerned about the Jedi Council's priorities, but Ahsoka pushed back, which she wouldn't have done before she left the order, accusing him of playing politics, saying that's why the people of the galaxy are losing faith in the Jedi. Obi-Wan tried to counter her by saying the people of Coruscant need their help now, but Ahsoka quickly replies "no, the chancellor needs you." Her rebuke of one of her former masters shows her growth since leaving the Jedi. Her willingness to speak up and especially her awareness of Palpatine's hold over the Jedi is exactly what Anakin needed just a few days later. Maul even tried to warn Ahsoka of Palpatine's plans for Anakin during their duel, so if Anakin had joined Ahsoka on Mandalore, Palpatine's manipulation may have completely unraveled, and without Anakin on his side, his chances of overthrowing the Jedi would be virtually diminished.
Ahsoka not even being mentioned in Star Wars: Revenge of the Sith has always made her feel a little out of place in other stories in Star Wars canon, but this flips the situation on its head, making Ahsoka, or rather her absence, one of the most important parts of Revenge of the Sith. Not only does the entire opening battle now likely exist entirely as Palpatine's means of separating Anakin and Ahsoka, but The Clone Wars season 7 also ties Ahsoka to a number of key events during the events of Revenge of the Sith. Obi-Wan even asks her to talk to Anakin about his assignment to spy on Palpatine, telling her "the council isn't always right. That's why I'm asking for your help," showing even he's come to understand her importance in saving Anakin. After Maul warns her about Anakin, she has a conversation with the Jedi Council where she misses Anakin by mere moments, right after he goes to meet with Palpatine, which is the meeting where Palpatine reveals himself as a Sith Lord. This recontextualization doesn't only make Ahsoka's existence finally fit into Revenge of the Sith, it actually makes her story one of the most important parts of the movie.