While actor Brad Pitt glamorizes Formula One by racing across movie screens, real-life drama has rocked Red Bull Racing, renewing speculation about the future of the team’s star driver and four-time world champion, Max Verstappen.

After two decades at the helm of Red Bull Racing, Christian Horner, 51, was dismissed as team principal on Wednesday despite orchestrating an unmatched era of dominance in Formula One.

Red Bull gave no reason for the dismissal, praising Mr. Horner for his “exceptional work over the last 20 years.” Under Mr. Horner’s leadership since 2005, Red Bull earned six Constructors’ Championships and eight Drivers’ titles, four with Sebastian Vettel between 2010 and 2013 and four more with Mr. Verstappen between 2021 and 2024.

In 2023, Red Bull enjoyed the most dominant season in Formula One history, winning 21 of 22 races. Mr. Verstappen set a record with 10 straight victories.

But Red Bull’s smooth ride began hitting its share of speed bumps, including internal tension, rumors of Mr. Verstappen’s potential departure, the recent success of McLaren Racing, and lingering questions about transparency amid a sexual harassment claim against Mr. Horner lodged before the 2024 season.

Mr. Verstappen posted an appreciative message in response to Red Bull’s shocking announcement. “From my first race win to four world championships, we have shared incredible successes, winning memorable races and breaking countless records,” he posted on social media. “Thank you for everything, Christian.”

Yet, Mr. Verstappen’s unhappiness with Red Bull’s current season may have been a primary reason for Mr. Horner’s dismissal. It began in early 2024 when a female employee at Red Bull accused Mr. Horner of sending sexually aggressive texts and pictures.

Mr. Horner denied the explosive allegations and was twice cleared of wrongdoing after investigations by Red Bull’s Austrian headquarters. His former Spice Girl wife, Geri Halliwell, supported him throughout the process. But there were immediate complaints of a lack of transparency, with Mr. Verstappen’s father, Jos, being one of the loudest critics. “He’s playing the victim when he is the one causing the problems,” the elder Mr. Verstappen said of Mr. Horner.

Rumors of Mr. Verstappen leaving Red Bull have persisted since and grown stronger as McLaren drivers Oscar Piastri and Lando Norris have owned the 2025 season with nine wins and 20 podiums between them over 12 races. Mr. Verstappen, who has two wins and five podium appearances this year, has all but conceded the Drivers’ title this year. “McLaren are not my rivals now,” the Dutchman said earlier this year. “I am just taking part in this world championship.”

Mr. Horner told his staff he was shocked by his dismissal, adding that he would remain employed by the company in another capacity. “When I arrived 20 years ago, with fewer grey hairs, I walked into a team and I didn’t know what to expect,” he said, according to the Daily Mail. “But I was immediately welcomed and, in two run-down buildings, we started to build what became a powerhouse in Formula One. Watching and being part of this team has been the biggest privilege in my life.”

Laurent Mekies, the principal of the Red Bulls’ sister team, Racing Bulls, will replace Mr. Horner. Mr. Mekies, an aerodynamics specialist, worked with Arrows, Minardi, Toro Rosso, and Ferrari before joining the Racing Bulls in 2024.

A Sky Sports F1 commentator, Martin Brundle, told the Daily Mail Mr. Horner’s removal “makes it more likely that Verstappen will stay” with Red Bull, adding that conflict with Mr. Horner “became personal in Team Verstappen.”

Red Bull and Formula One have an incentive to keep Team Verstappen happy while it negotiates a new United States media rights deal, projected to exceed $120 million annually.

Apple is reportedly in negotiations to acquire American broadcast rights as F1’s popularity surges in the country. Apple’s new F1-themed film, “F1,” starring Mr. Pitt, has become the tech giant’s highest-grossing release. The movie has generated about $300 million worldwide at the box office since its release last month. Along with a Netflix documentary series, “Drive to Survive,” now in its seventh season, the sport is attracting a younger and more diverse demographic.

Formula One’s current American media partner, ESPN, reported that F1 races are averaging 1.3 million viewers this year, up 17 percent from last year. For Red Bull, keeping its biggest star is imperative as the sport enters a new era.