While the reason for Horner's ousting has not been revealed, Red Bull senior advisor Helmut Marko has pointed out that performance concerns led to his exit, and that the decision was taken by the managing director of Red Bull GmbH, Oliver Mintzlaff. Newsweek Sports reported his comments:

Christian Horner’s long tenure as Red Bull Racing team principal came to an abrupt end in July, marking the close of a two-decade spell in charge. The team didn’t provide any specifics for the decision,

Nico Rosberg, the former Mercedes driver and Sky F1 pundit, believes Christian Horner’s sacking by Red Bull was “a long time in the making.” And the 2016 World Champion says it feels “completely unreal” to think that Horner is no longer in charge of the team he built into a winning machine.