[Storyteller's POV]
Celia's choice to side with Layland significantly shifted the people's general impression of the Kingdom. She had openly expressed her condemnation toward the King's lack of surveillance on the Nobles and civilians, especially, those who sided with Layland couldn't agree more.
She also revealed another stronger reason for siding with Layland—her non-consensual sacrifice. Since Brianna didn't even bother to hide her desire to sacrifice her, her senior, she didn't hesitate to tarnish her name by propagating the notion that she was plotting against her.
The people were enraged. No matter how highly they regarded the Hero, they still hated it when their people were treated like garbage. Celia was not a common person in this world, so they reacted violently. Many criticized the Kingdom openly, uncaring of the consequence.