It's not enough when Trump lies to report that Trump lied. Objective journalism requires an account of how many times and different ways he's lied on the subject in the past, and how the lie has progressed, and as context the fact that he generally lies.
You'd report they said that.
If they also failed 50 other drug tests in the last year, you'd report that as well. It would be part of the story.
Every story about every publicly elected figure is a story about credibility.
If they are known to lie, it's a part of all the other stories.
That would be an impartial assumption.
That would be reporting the facts.
Meanwhile, if you aren't powerful, even things you did that aren't relevant are added to the story.
The fact that in 1989 Trump took out an ad to try to get 5 innocent kids murdered by the state isn't part of every story about him.
It should be.
The fact that a president has no credibility is a part of the story, because it affects the story.
While each Trump lie lives it its own hermetically sealed glass case, an unknowable mystery