The following article contains spoilers for Obi-Wan Kenobi Part V.
The Star Wars canon is in almost constant flux. New shows and materials are always adding to it, or occasionally changing small details. With Obi-Wan and Darth Vader meeting again during the Obi-Wan Kenobi series, there was some concern that this would create quite a large plot hole in A New Hope. Yet, in Part V those concerns are laid to rest when the series finds a very clever fix that helps them to avoid any discrepancies with the original trilogy.
A New Hope was the film that started everything. It introduced the world to Obi-Wan Kenobi and Darth Vader and provided many hints about their tragic past. When they first met aboard the Death Star, Darth Vader told Obi-Wan "when I left you I was but the learner, now I am the master." For fans that meant them meeting again would present a contradiction. Yet, the dialogue isn't clear in regards to what time period Vader is referring to. In Part V of Obi-Wan Kenobi, there are a series of flashbacks, and within those flashbacks is another line that solves all these problems.
In these flashbacks, Anakin and Obi-Wan are training together before the Clone Wars. They're dueling to practice their lightsaber skills. Anakin is desperate to win, desperate to get recognition for his greatness and his strength. He sees no point in fighting with mercy since their enemies won't either. He cares only for victory while in the heat of battle. The fight escalates, but in the end Obi-Wan wins the duel. He sees how upset Anakin is, and tells him, "you're a great warrior Anakin, but your need to prove yourself is your undoing. Until you overcome it, a Padawan you will still be." This line helps to establish that no matter when they last met, Obi-Wan won't think of Anakin as a Master until he overcomes himself.
Anakin was constantly seeking the approval of others. First Qui-Gon, then the Jedi Council, then Obi-Wan. He never wanted to fail anyone in his life. This is partially what drove him to the dark side. And Darth Vader in Obi-Wan Kenobi is still suck in that cycle, seeking validation from his old Master. After all, his biggest loses have always been against Obi-Wan. He wants to beat him fairly, he needs to, it may even be why he let him go in Part III. At this point in time, Vader is still a slave to his desire for validation.
The context of their meeting in Episode IV has now changed, that is certain, but that doesn't make it a plot hole. Instead of that line referring to Revenge of the Sith, it's now referring to the fact that Vader no longer seeks Obi-Wan's or anyone else's approval. He knows that he is powerful, he knows that he is feared, and he knows that there is hardly anyone left in the galaxy who could best him. He is a Master of the dark side and a Master of himself. Obi-Wan's approval no longer means anything to him. During Obi-Wan Kenobi he is still a learning that, by A New Hope he has mastered it.
Obi-Wan Kenobi has taken a lot of care in making sure that the Star Wars canon stays intact. Despite "killing" the Grand Inquisitor and the suspected plot holes in Episode IV, the series has done a wonderful job of offering solutions to all those issues. Using the flashbacks in Part V to explain the line in A New Hope is an incredibly clever and simple way to keep the story moving forward while preserving the canon of the original trilogy.
New episodes of Obi-Wan Kenobi stream Wednesdays on Disney+.