SCREENRANT VIDEO OF THE DAY SCROLL TO CONTINUE WITH CONTENT Summary The Marvel Cinematic Universe introduced time travel in Avengers: Endgame, but four years later, Loki season 2 has broken one of the major rules established by Marvel Studios' 2019 movie. After Thanos snapped away half the universe in Avengers: Infinity War, Earth's Mightiest Heroes set out to figure out how to travel through time in order to undo the devastation wreaked by the Mad Titan.
This goes against everything Smart Hulk, and by extension Avengers: Endgame, established in terms of how time travel works in the MCU. If changing the past affected the future, then everything from the Avengers' time heist would've had ripple effects and when they returned to their present, it would've been completely different. Thanos may never have been able to achieve the snap in the first place, and it would've been an anticlimactic ending to the Infinity Saga.
Endgame took place before Sylvie killed He Who Remains, so the MCU was existing within the Sacred Timeline, and any changes to it would've been pruned by the TVA. Hulk's time travel rules may have been true for the Sacred Timeline, due to factors outside his and the audience's knowledge, but now that the multiverse exists, time travel doesn't work in the same way.
Loki Season 2's Time Travel Rule Break Has A Major Diss Against Endgame When Loki, OB and Mobius are having their conversation across time, Mobius realizes that Loki is changing the present by changing the past, and OB says "there's no flaw in that logic." Although the dialogue doesn't call out the Avengers or Endgame by name, it feels like a major diss to the 2019 MCU movie due to how many times Endgame's logic has been called into question.