Red Bull says Christian Horner has been released from his role as longtime team principal of its Formula 1 team. Red Bull did not give a reason for the decision in a statement Wednesday, but thanked Horner for his work and said he will “forever remain an important part of our team history.

After 20 years at the helm of Red Bull Racing, Christian Horner is out as team principal and CEO, effective Wednesday. The bombshell move comes at a tumultuous time for the Formula One team as it struggles to create a competitive car, sitting fourth in the constructors’ standings largely thanks to Max Verstappen’s performances this season.