Noam Chomsky, the author of the classic media critical book "Manufacturing Consensus" said and I tend to believe him that the papers the serious business players read can't just make up "facts" whole sale out of thin air, because that would hamper the ability of the players to operate in the real world. the Oligarch media does not mislead by fact invention, it lies by omission, and constructing narratives with carefully hand picked set of "facts".

and in this case the headline says "US officials warned the White House that Russian intelligence was using Rudy Giuliani to funnel disinformation to Trump" ...


so most probably some officials tried to present "warnings" but we can't say if these warnings were presented in good faith or in order just to be able to leak this ...

the warnings might be true or false but as you can see the Business Insider does not claim the warnings are true.

You need the ability to read what the media actually says.