The sudden downshift in energy was enough to make some fo the group unsettled. Grace, Reese, and Isa were clearly a little off. It wasn't that Isa was not prepared to kill anyone, but she knew exactly the danger and fear that those who had been ambushed by bandits would feel.
Being a merchant, Isa was able to meet many people who had escaped with their lives because of bandits trying to rob them. Seeing that there were three carriages here just proved that people had died because of the scum they had just worked to kill in self defense. It was tragic and Isa felt for the loss of lives because of them.
This was different for Reese and Grace. These weren't monsters like the blood moon cult members that pretended to be students in the tournament. They weren't so far gone that these people were becoming monsters. Reese had rationalized his actions because he was able to fight them as monsters. He dehumanized them easily. That was very similar to how Grace thought of it.