Something virtually everyone who follows Marvel knows looks to be happening, as due to the movie being delayed it sounds like James Gunn will to another pass on the Guardians of the Galaxy Vol. 3 script; according to his brother.
Sean Gunn told ComicBook.com in an interview:
“I know, you know…I think my brother may do…he may do another pass, in which case I would read that version.”
Honestly, this news isn’t really news and it’s unfortunate that clickbait sites and anti-MCU YouTubers are blowing it out of proportion and accusing Disney of “studio interference” to ruin Guardians 3. The tweaks are not due to the success of Avengers: Endgame, and anyone who actually followed the saga of James Gunn and Guardians of the Galaxy Vol. 3 would know that right away.
Originally Guardians of the Galaxy Vol. 3 was going to be the May 2020 movie, but then the James Gunn firing situation happened. Gunn himself went on Facebook Live last April to say how if all went well the movie would be out two years from that broadcast, which would’ve made it the May 2020 movie. When Gunn was fired another movie had to take its spot (Black Widow) and Disney then only had two movies to release in 2020 so they abandoned the July date they claimed, which Sony jumped on for that Morbius movie everyone can’t wait for.
If Guardians of the Galaxy Vol. 3 ended up being the May 2020 movie, it would’ve been the first release of Phase 4. Now, it’s not even in Phase 4. That means anything it setup for Phase 4, such as introducing The Eternals, would have to be changed now that the movie is coming long after all of those movies.
So there’s the history of Guardians of the Galaxy Vol. 3, and any script changes Gunn would need to do wouldn’t be out of “studio interference” following the Endgame success, it’s simply to adjust what would’ve been the first Phase 4 movie into a Phase 5 movie.