Larry David’s Seinfeld career is a recurring topic in Curb Your Enthusiasm, which climaxed when he brought the cast back for a non-canon reunion. Curb Your Enthusiasm premiered in 2000 as a comedy series following a fictionalized version of Larry David as he navigates Hollywood post-Seinfeld. The show is almost an extension of Seinfeld, showing Larry in everyday American life where his lack of social graces constantly gets him in trouble, similar to what happens to George Costanza in nearly every episode of Seinfeld.
Although Larry David’s career extends beyond Seinfeld, he makes a point that everyone knows him as the show’s co-creator, and this status can give him a leg up when he needs one. Julia Louis-Dreyfuss, Jerry Seinfeld, and Jason Alexander recur throughout Curb Your Enthusiasm, typically in ways where they’re annoyed with Larry if he needs something. The actors usually made separate appearances until Larry brought them back to reprise their roles in an official Seinfeld reunion in season 7. Larry and Jerry have written the long-awaited episode, though the former is only using it as a way to win back his ex-wife Cheryl.
Since this Curb Your Enthusiasm episode aired, fans have debated whether or not the new plotlines within the reunion show are considered Seinfeld canon. Within Curb Your Enthusiasm’s fictional version of Hollywood it’s made to be a legitimate episode, but in the real world, no, it’s not canon. Certain aspects like Cheryl David - not actress Cheryl Hines - being cast in the episode indicates the Seinfeld reunion doesn’t exist in any real-world context, so can’t be considered an actual extension of the original series. Similarly, the real David has always been vocal about having no interest in doing a Seinfeld reunion. He described Curb's episode as a way to do a reunion without actually doing one, just bringing back the cast and their characters in a funny, more relaxed manner.
Some of the confusion about the canonical aspect of Curb’s Seinfeld special comes from an actual script being written for the fictionalized episode by one of Seinfeld’s former writers. The Curb Your Enthusiasm episode is technically the first time since Seinfeld’s season 9 finale the cast has been together in a scripted reprisal of their roles, so fans have wondered whether that suggests they can include the new developments in the characters’ biographies. The original set of Jerry’s apartment was recreated and several recurring cast members like Wayne Knight were brought back for Curb’s table read, so it seemed to have a trace of legitness.
Curb’s Seinfeld special included new details like Jerry having donated sperm to Elaine to have a baby and George marrying a woman who amassed a fortune from developing the iPhone app “iToilet.” Most of the fake episode deals with the plot written by Larry, wherein George desperately tries to get back with his wife. The episode also includes a reflective joke from Jerry when he says “we already screwed up one finale,” referencing Seinfeld’s poorly received series finale. As angry typically fans do, viewers wanted Seinfeld to come back and properly end the story for its beloved characters, which Curb Your Enthusiasm’s episode essentially achieves - albeit non-canonically.