I personally have no problem killing OCs. Half of them already are predetermined to live or die( I might change my opinion later though if I see that killing them/ letting them live benefits the plot more). As long as it saves my canon character darlings( yes, I have them, and I am not sorry), their death is justified. Besides, nobody is going to cry for an OC( well, except for maybe other characters in-universe, and even then I try to avoid having them be loved by many other characters, because universal approval of an OC leads to Mary Sues/ Gary Stus, so in most cases few are going to miss them), so better sacrifice them than my beloved canon characters. And yes, I am the terrible writer who would save/ bring back her beloved characters at all cost, even if the most logical/ consistent way would require sacrificing the lives of the one or two OCs.