SHIELD was present during the final battle of Avengers: Endgame, which justifies the fact that people know so many details about the event in the MCU.
Who confirms this is the Marvelwhich on its official website says that an agent of SHIELD, who was on the battlefield, wrote a memoir about what happened in Avengers: Endgamewhich includes a chat with Gavião Arqueiro.
“If you’re looking for a first-hand account of the Battle of Earth, be sure to pick up a copy of the memoir “I Was There…”, written by a SHIELD agent detailing “the clash between Earth’s heroes and the alien scourge that threatened our fragile planet.” The book includes a conversation with Hawkeye, and a first-hand account of Tony Stark using the Infinity Gauntlet (even though the author was 2 km away).” – Says the description of the Marvel.
The question of how people in the MCU knew so much of the battle came up in the Ms. Marvel, which shows that Earthlings are even aware of who the Guardians of the Galaxy are.
Avengers: Endgame concluded the Infinity Saga in marvel studioscurrently being the second highest grossing worldwide box office of all time.
The severe course of events generated when Thanos wiped out half the universe and fractured the Avengers’ ranks leads the remaining heroes to attempt one last move in Marvel Studios’ grand conclusion of twenty-two films.