According to the New York Post and some other conservative media, Darrell Brooks, the man who drove his car into a parade in Waukesha killing at least six people, had pro-Hitler, anti-semitic and violently anti-white material on his social media account. Googling on [Darrell Brooks Hitler] I found no mention of it in any mainline source. The New York Times has a long story on Brooks with no mention of those facts — and the claim that "The suspect’s motivations are unclear." The Wall Street Journal has had multiple stories on Brooks but I cannot find any mentioning the social media.
It is possible that the conservative sources are lying but I think it unlikely, since if they were I would expect the NYT or other left of center media to call them on it. It looks very much as though the mainline media are deliberately hiding facts they don't want their readers to know.