According to deontology, sacrificing one life to save another is bad. However, when you do any action (eg drive a car, like social media posts), you cause butterfly effects that will cause many different people to have harm caused to them. In other words, you are knowingly causing harm to people every time you do anything. Would your existence thus be immoral?
Clearly consciously sacrificing a life and unintentionally setting in motion a very indirect chain of events which leads to someone dying are not the same thing, especially in deontology which cares much more about rules and principles than effects.
Frankly butterfly effects are a bigger problem for forms of consequentialism/utilitarianism, where you do care solely about ends, and are faced with the problem that not only might the utility impact of all those "butterfly effects" you cause vastly exceed the ways you try to help people, but if you choose to factor them in they also raise the prospect that whether you're a moral person or not is completely incalculable...