More Marvel movies from several franchises, including Spider-Man: Across the Spider-Verse, are delving into the concept of the multiverse, leading many to question if it was Loki, Miles Morales, or Doctor Strange who broke it in the first place. Since the MCU's Multiverse Saga began, the blurring of franchises has become more common. From the inclusion of variants in the MCU from previously non-canon TV shows like Inhumans to the X-Men and all three live-action Spider-Men crossing over, the multiverse has almost made every Marvel property in history somewhat canon to the MCU.
https://screenrant.com/who-broke-mcu-multiverse-loki-doctor-strange-miles-morales/