There's a long line of research in the study of political communication that researchers call “blaming the referees”. It's a strategy that political elites can often use to try to diminish trust in verifiably accurate news sources.
There's a distinction to be made between news sources that have things like corrections policies and that punish journalists when they get facts wrong versus other organizations that also sometimes frame themselves as being news organizations, but are primarily opinion organizations.
When it comes to the more trusted places—the places where they're engaging in what we would think of as more legitimate journalism, which doesn't mean they're always right, but it means that they correct themselves when they're wrong—it's a danger to diminish trust in those organizations without evidence.
A lot of times, a strategy that political elites use is to try to diminish the amount of trust in mainstream news sources. The purpose of that diminishing trust is then to not face consequences from voters at the ballot box, as an example, for behaviours that lawmakers or others may engage in.