The news has just broke that Colin Trevorrow has exited Episode IX, and Lucasfilm now has their second set directorial departures in a row.
While we are largely left to speculate, The Hollywood Reporter has some more details in regards to what exactly happened:
Sources tell The Hollywood Reporter that script issues have continued to be an issue during Episode IX’s development, with Trevorrow having had repeated stabs at multiple drafts. In August, Jack Thorne, the British scribe who wrote the upcoming Julia Roberts-Jacob Tremblay movie Wonder, was tapped to work on the script.
Sources say that the working relationship between Trevorrow and Lucasfilm head Kathleen Kennedy became unmanageable. Kennedy, who had already been through one director firing/replacement on the Han Solo spinoff movie, was not eager for a sequel and tried to avoid this decision.