It was only a matter of time before the trailer for Spider-Man: Far From Home was going to raise new theories about Avengers: Endgame. It all started with the statements from Kevin Feige, CEO of Marvel Studios, related to the moment in which the events of Far From Home took place so that everyone could formulate a thousand and one theories.
Feige said that the movie happened after Infinity War, but some fans consider that it was just an irresponsible statement or a marketing strategy, and that it did not necessarily happen in that order. For example, in the trailer when Peter shows his passport, we see that the dates of issue and expiration are blocked, this means that Jon Watts, director of the film, wants to keep secret the year in which the trip to Europe is made.
So on the one hand, we have a theory that says Peter Parker does not get the passport after Avengers: Endgame, but before, and that the bus trip we see at Avengers: Infinity War, is showing Peter’s return from Europe to New York, Peter Parker will remain dead and we do not know what will happen in the last film of the third phase of the Marvel Cinematic Universe.
Another theory points out that the events that will occur in Endgame will end up undoing everything that happened in Infinity War and the Avengers will restore order with the Infinity Gauntlet. This means that Thanos will never attack the Earth, therefore Peter Parker will never get off the bus that is taking him to the airport to take off to Europe and Infinity War will be the prologue of Far From Home.
Now, according to this theory, Spider-Man: Far From Home happens right after Avengers: Endgame, but in a time restored, not in a normal timeline, because the Avengers could only revive everyone with the Gauntlet and leave things as they are. And not, that the heroes would have returned to the past and reestablish reality as if nothing had ever happened.
The fans are opting for the story of the restoration of reality, because when Nick Fury ambushes Spidey in the trailer, he does not detect Fury’s arrival with his arachnid sense, consequence, they say, of the mismatch caused by Thanos. But above all, this seems to be the most plausible hypothesis because, if Spider-Man had not had to fight with Thanos he would not have received the Iron Spider suit, so we do not see him using it in Europe.