Dan Slott, who has written more issues of Spider-Man than almost anybody in the character's publishing history, was none to keen on one particular element of the character's portrayal in Avengers: Endgame. And, no, it isn't his relationship with Tony Stark that is the issue, but rather the moment, late in the film, that Spidey's Iron Spider costume (...so...maybe it is a little about Tony) goes into "instant kill" mode and the friendly neighborhood wall-crawler wages a brief but brutal all-out war on Thanos's troops. Slott objected, saying that even in those circumstances, Peter Parker should not resort to lethal force.
Slott has been sharply critical of Zack Snyder's DC movies in the past, a series that drew criticism in part because the climax of Man of Steel included Superman executing Zod, something John Byrne had done in equally controversial comics in the 1980s. After fans and Twitter users got predictably upset at his (fairly mild) criticism of Endgame, Slott clarified himself a few times, first saying that the statement was just his opinion, and that since Peter is a fictional character, one person's opinion isn't binding. Later, he added that superhero fans in general have an easier time ignoring the logical and scientific issues with characters who fly and have super-strength than they do with those characters avoiding deadly force.
There was 1 moment I did NOT like in all of AVENGERS: ENDGAME.
Peter Parker shouldn't kill. Even when it comes to Thanos' evil army of alien spacehounds.
But not liking 1 moment out of 3 hours and 2 minutes ain't that bad. :) pic.twitter.com/GAhuZslVgf— Dan Slott (@DanSlott) August 12, 2019
There is a constant give-and-take among creators and the audience as it pertains to adaptations of comic book movies. In almost every case, the version that comes to the screen will not be a 1:1 adaptation of the version on the page. That means you sometimes get people like veteran comics writer Mark Waid, whose Kingdom Come presented the definitive Superman for a generation of fans, being passionately angry about Man of Steel, and Slott being annoyed by some elements of Endgame. Slott later acknowledged as much, saying that he still holds characters like Peter to "a different metric" personally.
Spider-Man: Far From Home is still in theaters, and Avengers: Endgame was just made available on digital services. Upcoming Marvel Studios projects include Black Widow on May 1, 2020, The Falcon and The Winter Soldier in Fall 2020, The Eternals on November 6, 2020, Shang-Chi and the Legend of the Ten Rings on February 12, 2021, WandaVision in Spring 2021, Loki in Spring 2021, Doctor Strange in the Multiverse of Madness on May 7, 2021, What If…? in Summer 2021, Hawkeye in Fall 2021, and Thor: Love and Thunder on November 5, 2021.