When Lucas (Caleb McLaughlin), Dustin (Gaten Matarazzo), Steve (Joe Keery), Nancy (Natalia Dyer), and Robin (Maya Hawke) help Max evade Vecna, they eventually discover that each of his kills is a goal for the Upside creates Down and that Max’s death would result in the final gate opening he needs to bring the Upside Down down into the real world. And although Eleven manages to overpower Vecna and restart Max’s heart after his attack, the damage is done: the fourth gate opens as Max dies, and Hawkins is suddenly thrown into an apocalypse.
However, the giant rifts close when Eleven revives Max and seemingly traps Steve, Nancy, Robin, and Dustin in the Upside Down. Two days later, however, the teens are back at Hawkins and ready to stare at the head one more time as the cracks open up again. This left fans confused, with Redditor u/zunrt writing: “IIRC, the portal crack went through Eddie’s trailer so it got wiped out… We see Steve, Robin and Nancy back in Hawkins at the end. When they jump on the crack, where do they go? Since there’s kind of nowhere to land, in Hawkins he just opens up to the air.”