Doctor Strange in the Multiverse of Madness director Sam Raimi confirmed which Earth Defender Strange is from.
On the film's audio commentary, Raimi revealed that the gray-templed Stephen Strange variant hails from Earth-617, the multiversal next-door neighbor of the Marvel Cinematic Universe, which is set on Earth-616. In the comics, Earth-617 split from mainstream continuity after its version of Gwen Stacy avoided being killed by the Green Goblin and went on to become the superhero Spider-Woman. Earth-617 was later invaded and almost overrun by the Nightmare realm, and was ultimately destroyed during the 2015 Secret Wars storyline.
Raimi announcing Defender Strange's Earth-617 origins follows several months of fans debating the MCU's place within the wider Marvel Universe. While Doctor Strange in the Multiverse of Madness establishes Earth-616 as the setting of the MCU, this clashes with existing canon which states the mainline comics take place on that world, with the movies' events unfolding on Earth-199999. Ms. Marvel star Iman Vellani has even weighed in on the debate, noting that she continues to argue about this aspect of Doctor Strange in the Multiverse of Madness continuity with Marvel Studios President Kevin Feige.
Multiverse of Continuity
By contrast, the Doctor Strange sequel's place within the MCU timeline has proven less controversial with fans (so far, at least). Disney+ recently updated its chronological MCU viewing order, which positions Multiverse of Madness after Eternals but before Hawkeye, Moon Knight and Ms. Marvel. Although Spider-Man: No Way Home doesn't appear in the timeline due to licensing issues, considering that film is set around the same time as Hawkeye, it likely takes place before the Master of the Mystic Arts' second solo outing, too.
Other interesting factoids to emerge out of the Doctor Strange in the Multiverse of Madness audio commentary include surprising trivia concerning inter-dimensional beastie Gargantos and shadowy organization The Illuminati. Regarding Gargantos, co-producer Richie Palmer explained that the creature's eyeball was based on a scan of star Elizabeth Olsen's own eyes, foreshadowing the Scarlet Witch's villainous role in the film.
Where The Illuminati is concerned, screenwriter Michael Waldron confirmed that The Wasp was nearly included as part of the elite council's line-up. "Originally in the first draft [of Doctor Strange in the Multiverse of Madness] The Wasp... was in The Illuminati," he said. "And The Wasp shrunk down and flew at [the Scarlet Witch] and Wanda clapped her hands and smushed The Wasp."
Doctor Strange in the Multiverse of Madness is now streaming on Disney+.
Source: Doctor Strange in the Multiverse of Madness audio commentary