[AAP] Ask a Philosopher - Question from Husamettin Ozturk

What is the name of the fallacy /cognitive bias (I do not know under which category the attitude I am about to talk about falls) where a person concludes about or scrutinizes occurrences based on what they observe, or in other words, ignoring the root causes or background of an event? To illustrate, (I will try to refrain giving actual examples in order to avoid politicization of the question), if X slaps Y, and Z judges the situation by the way it was reflected to her, neglecting the fact that Y is the one who slapped X for no reason beforehand.