As Qi'ra spoke personally with Sidious and outlined her plans to destroy him, Qi'ra sent the Vermillion to attack the interdictor. The Vermillion was attacked by TIE fighters and TIE/IN interceptors, but they were unable to prevent the ship from crashing directly into the interdictor, destroying both. Escape pods were deployed from the Vermillion, and Sidious ordered they all be destroyed, allowing for no one to escape.
The destruction of the Vermillion allowed for Qi'ra and the Oprhans to escape from the Imperials aboard the Siroto and as they left, Chanath Cha asked Qi'ra if they should pick up any potential survivors from the escape pods, Qi'ra thought for a moment before declining, adding that they could honor their sacrifice by seeing her plans through to the end.
The fact that Qi'ra survived was later inadvertently revealed to Vader by Cha. When Cha confronted Vader, he informed her that she would not avenge Qi'ra's death, which surprised the hunter. Vader sensed this and realized that Qi'ra had actually survived, adding that his Master would be fascinated to learn of this.