Red Bull mastermind Adrian Newey to leave at the end of the season
The BBC and Germany's Auto Motor und Sport reported last month that the Briton had told Red Bull he wanted to move on following allegations about team principal Christian Horner.
Horner was cleared in February of alleged misconduct towards a female employee, who has lodged an appeal against the outcome.
"For almost two decades it has been my great honour to have played a key role in Red Bull Racing's progress from upstart newcomer to multiple title-winning Team," Newey said in a statement.
"However, I feel now is an opportune moment to hand that baton over to others and to seek new challenges for myself."
Newey cars have won 25 drivers' and constructors' championships for Williams, McLaren and Red Bull. His 2023 car was the most dominant in the sport's history with 21 wins from 22 races.
Red Bull said the 65-year-old would step back from Formula 1 design duties but would continue to attend specific races until the end of the current season.
"All of our greatest moments from the past 20 years have come with Adrian's hand on the technical tiller," Horner said. "His vision and brilliance have helped us to 13 titles in 20 seasons.
"For me, when Adrian joined Red Bull, he was already a superstar designer. Two decades and 13 Championships later he leaves as a true legend."
Red Bull are currently dominant with triple world champion Max Verstappen but Newey has been a regular target for top teams.
He has been reluctant to leave England, where most of the teams are based.
Ferrari, who will have seven-times world champion Lewis Hamilton joining them next season from Mercedes, and British-based Aston Martin have been named as possible future employers and have made overtures.
Red Bull are finishing their partnership with Honda at the end of next season and making their own engine with backing from Ford when the sport starts a new power unit era in 2026.
The team have been going through turmoil since before the start of the season, with Horner in the spotlight and having issues with Verstappen's father Jos and Red Bull motorsport consultant Helmut Marko.
Formula 1 veteran Marko and the Verstappens are close, with Max linking his future at the team to the Austrian remaining.
Newey is regarded as equally vital to Red Bull's success as Verstappen, even if the Briton is not a one-man band and has a team of highly-rated designers and aerodynamicists working with him.