Warning! SPOILERS for Obi-Wan Kenobi.
A New Hope and that he was never the master he insisted he was. A large majority of Obi-Wan Kenobi has centered around the relationship between Kenobi and Vader, leading up to what will surely be their true rematch in Obi-Wan Kenobi episode 6. However, a certain sequence found in episode 5 provides more context to Vader's line in A New Hope.
A New Hope was released in 1977, then simply titled Star Wars, and it was the first film to hint at a relationship between Obi-Wan and Vader. Since then, the prequel trilogy, Star Wars: , and now Obi-Wan Kenobi have massively developed the relationship between the two iconic characters. With Obi-Wan Kenobi episode 5, their very first meeting in Star Wars from 1977 is entirely re-contextualized.
The scene that does this is a flashback featuring Anakin Skywalker and Obi-Wan Kenobi from around the time of episode 5 while also hinting at the same happening in episode 6, but it completely re-contextualizes Vader and Obi-Wan's meeting in A New Hope. The line in which Vader insists he is the master over Kenobi now is changed to show that Vader simply thinks he is the master. The scene reinforces this by showing Vader to be making all the same mistakes. He is blinded by his hatred of Kenobi, and his need to be victorious over his old master, allowing Obi-Wan to sacrifice himself to ensure Luke and Leia escape on the Falcon.
In doing so, Luke and Leia become a much bigger problem for the Empire than an old Kenobi ever would have been. As Luke and Leia, both appearing in Obi-Wan Kenobi, are integral in destroying both Death Stars and ending the reign of the Empire, Vader's short-sightedness at simply needing to beat Kenobi is almost the act that is entirely responsible for the Empire's many defeats following A New Hope.
This new context lessens the differences between Anakin and Vader in some ways. A lot of the time, Star Wars presents the two as separate beings, with Vader often stating throughout the saga that he destroyed Anakin. Obviously, given Vader's redemption in Anakin the former Jedi, not entirely Vader, the Dark Lord of the Sith. All of these reasons only go to show why Obi-Wan Kenobi reimagines one of the most iconic scenes from the original Star Wars, 45 years after its initial theatrical release.
New episodes of Obi-Wan Kenobi release every Wednesday on Disney+.