Where did you hear this? Please don't tell me from that clown slugzilla on superherohype Jeff Sneider said this in 2018.
https://www.tracking-board.com/inside-the-drama-surrounding-foxs-new-mutants-including-a-top-secret-new-cast-member-exclusive/
"For starters, I’m told that the creative differences between director Josh Boone and Fox execs have been blown out of proportion by fanboy bloggers who are all too eager to make a mountain out of a molehill, and that Boone ultimately delivered the movie that he and co-writer Knate Lee originally agreed to make. There is no “Josh Boone cut” gathering dust in a locked vault on the Fox lot."
The simple fact is that making movies of this size is a complicated process that involves many compromises, and a corresponding number of cooks in the kitchen. Sometimes there are too many cooks, and that’s kind of what happened with regard to New Mutants.
Boone and Lee wrote the initial drafts of the script, but they were replaced and brought back multiple times. The studio even assembled a writer’s room to tear apart the script and put it back together. So while Boone and Lee might have their names on every draft, agency sources insist that this film was written by committee.
According to those sources, here are all of the writers who had a direct hand in the New Mutants script: Scott Neustadter & Michael Weber, Josh Zetumer, Chad & Carey Hayes and Seth Grahame-Smith, plus there were six more guys in a writer’s room tasked with generating ideas for the film. Interesting to note that there wasn’t a single female writer involved at any point, but that’s another sad story for another dark day.
At first, Boone and Lee wanted to make a horror movie, but Fox was initially resistant to that idea, as the studio didn’t want to go “full horror.” Sources say that Fox demanded a PG-13 rating and pushed back against the film’s horror elements, such as excessive blood and scares. Eventually, everyone got on the same page, and together, they set out to make a YA movie that felt like a cross between Stephen King and John Hughes. Fox film chief Stacey Snider is basically quoted as calling New Mutants a superhero movie set in a Breakfast Club-like setting whose genre is more like The Shining than “let’s save the world.”
At that point, Fox decided that instead of doing the three days of additional filming required to complete the YA movie that everyone had initially agreed to go make, the studio would change course and make a new version of the movie that was straight-up horror, which was what Boone and Lee originally wanted to do in the first place. It’s a little like a diner sending back a meal at a restaurant — not because there was something wrong with it, but because they simply changed their minds and wanted to order a different entrée, or movie, in this case.
Those close to the director said he always felt a bit neutered during principal photography, as he was forced to tone down the violence in order to avoid a dreaded R-rating. And because Boone was contractually obligated to shoot what was in the script, there was only so much he could do despite his and Lee’s best instincts. Sources say that while the second half of New Mutants is basically locked at this point, the first half of the film needs some work, and that Boone will likely add a bunch of scares that didn’t initially appeal to Fox execs. He and Lee might even stand a better chance of getting what they want now than they did during the initial development phase. In the end though, insiders chalk up the confusion surrounding the tonal identity of New Mutants to the lack of a strong producer on set, as lead producer Simon Kinberg was often busy making his own X-Men movie, Dark Phoenix.
About Mr Sinister being teased along with Essex: "Meanwhile, remember the Essex Corporation that was teased at the end of X-Men: Apocalypse? Well not only was New Mutants going to feature that mysterious company, but The Tracking Board has learned that Jon Hamm was originally going to appear as Mr. Sinister in a tag at the end of New Mutants, and Boone filmed material that led up to that reveal, only for Fox to change their minds after shooting had been completed. Now it’ll be Antonio Banderas playing an unspecified villain (one who isn’t expected to be Mr. Sinister) in the New Mutants tag. Additionally, Mr. Sinister wasn’t the only character Fox steered away from New Mutants, as Warlock appeared in early drafts of the script before the character was deemed too expensive."
The New Mutants situation may be a mess, but insiders believe it’s a fixable one. By all accounts, it has been a stressful shoot for Boone, but he has fought the good fight in the name of making the best movie possible for fans. If the studio truly thought this was his fault, they probably would’ve fired him and brought in someone else like Lucasfilm did with Ron Howard on Solo, but Fox execs know this problem is of their own doing. That’s why they aren’t kicking him to the curb, and why they’re allowing him to both write and direct the new material. Plus, he makes a convenient scapegoat.
Despite a full plate, those close to the director say he’s committed to seeing his vision for New Mutants through to the end, though it’s been frustrating for members of his cast and crew to read so much inaccurate speculation online.