First off, both the writer and the director had left the project under various circumstances. Writer Jeff Loveness' departure is being blamed on the critical and commercial failure of Ant-Man and the Wasp: Quantumania (2023), which he wrote the screenplay of. Director Destin Cretton left the movie to make Shang-Chi 2. Michael Waldron from Loki (2021), Doctor Strange in the Multiverse of Madness (2022) and Avengers: Secret Wars (2027) was hired as the new screenwriter on November 28th.
On 18 December 2023, Kang actor Jonathan Majors was found guilty on aggravated assault charges which were brought against him by his ex-girlfriend in March 2023. Quickly following his indictment, Marvel would announce Majors' removal from future MCU projects. There also has been plans to re-do the next Avengers films, as Kang was no longer being considered as the main antagonist. Marvel had also renamed the movie to simply "Avengers 5".
In January 2024, it was speculated that the film might be facing a significant delay due to pre-production issues.