Former Disney CEO Bob Chapek’s attempt at rewriting his disastrous tenure atop the studio isn’t causing panic inside the Mouse House, we hear. The impending release of Chapek’s memoir, “Behind the Castle Walls,” out Tuesday, is being viewed as “a bit of a yawner,” one Disney insider tells Page Six Hollywood.

“The Chapek thing is done and dusted from [Disney’s] point of view,” the source tells us — adding that internally, the tome is being viewed more of an anti-Bob Iger screed.

The book tells the entertainment exec’s side of his chaotic and ultimately unsuccessful three-year tenure as Disney CEO — as well as his own “hero’s journey” rising from small-town Indiana to one of the most high profile jobs in Hollywood.

In the book, seen by Page Six Hollywood, Chapek details his perception of his predecessor, and successor, Iger’s constant campaign to undermine him at every turn, including: His off-putting demeanor during their initial CNBC joint interview on Chapek’s first day (which made Chapek believe that Iger “didn’t want to let go of the ball”), Iger’s bashing of him in private, snubbing him during his retirement speech and undermining him during Disney’s fraught “Don’t Say Gay” bill controversy.

Chapek writes in the book: “While the board and I were having internal discussions about how to respond to the legislation, which had yet to officially pass, Bob tweeted, ‘I’m with the President [Biden] on this! If passed, this bill will put vulnerable, young LGBTQ people in jeopardy.’ He was implying none of this would have happened on his watch, and all this was a simple and clear decision for the company. To him, it was the perfect opportunity to use the situation to show he was right, and I was wrong.”

The controversy over Disney’s response to the “Don’t Say Gay” bill was among the biggest missteps attributed to Chapek’s tenure, as was the nasty public fight with Scarlett Johansson over the release of “Black Widow” in 2021. (The star sued Disney for breach of contract, alleging that simultaneously releasing the film in theaters and on Disney+ lowered her pay, and Disney responded by publicly bashing the star and bringing up Covid.)

The suit was settled in 2021.

Chapek now says he was the fall-guy in the ScarJo snafu: In an interview with the Wall Street Journal last week, Chapek said the harsh stance on Johansson at the time came from Disney’s head of comms and it was approved by Iger.

Despite being CEO, Chapek said he was told to let Iger handle any matters dealing with talent. “I thought the company statement was very harsh. I thought bringing up the Covid situation and the theoretical insensitivity was, uh, nontraditional,” he said.

In the book, Chapek writes that Iger further used the backlash, “as evidence of my perceived lack of relationships with the creative community.”

The book paints Chapek as a humble Midwestern Joe, while Iger was an alleged egomaniac who apparently once told Chapek he was modern reincarnation of Walt Disney himself, Chapek writes. (We’re told that Chapek’s feeling of being an outsider “was a real thing inside Disney,” per a source.)

The Disney insider adds that studio brass are more concerned with a different upcoming book, Wall Street Journal reporter Robbie Whelan’s tome about Iger and the Magic Kingdom, “The House of Mouse,” due in December. Disney and Iger reportedly even hired high-power attorney Charles Harder to play defense against the book that’s also highly anticipated around town.

Page Six Hollywood has previously reported on Iger’s concern about the upcoming book — and how it factored into his decision to partner with a former Hillary Clinton speechwriter and communications expert, Dan Schwerin, on a sequel to his own memoir, “The Ride of a Lifetime.”

We also reported how Iger coincidentally was featured in a Harvard Business Review interview last week firing back at Chapek (without naming him) on the same day excerpts from Chapek’s book dropped in THR and Vanity Fair dissing Iger.

One aspect of the book folks at Disney aren’t buying is that Chapek “did nothing wrong” during his time atop Disney. “Give me a break,” an insider huffed.

But despite all the internal studio iconography of Iger, Chapek does still have sympathizers inside Disney who think he was not given a fair shot thanks to Iger’s ego. “Iger retired seven times because he couldn’t ‘let go,’” a former Disney employee told us.

For Iger, Chapek’s books comes as the former Disney exec has been intently interested in crafting his legacy now that he’s finally moved on to his next career as the future face of the LA Lakers ownership group.

We have reached out to Disney about the book, and Iger has yet to respond publicly about the claims made by Chapek.