In a recent interview on the red carpet at Doctor Strange in the Multiverse of Madnessthe president of Marvel Studios Kevin Feig confirmed the connection between the television series Loki and the movie Spider-Man: No Way Home that everyone imagined.
Feige made it clear that what Loki and Sylvie did at the end of their series allowed the events of Spider-Man: No Way Home Y Doctor Strange in the Multiverse of Madness were possible.
There is always a method to madness. Even in the multiverse. And for Marvel fans who know what Loki and Sylvie did at the end of their series, know that it made all of this possible. The One Who Remains is gone and that has allowed a spell to go wrong in Spider-Man: No Way Home, leading to the entire multiverse going pretty crazy in this one.