Earlier quoted context omitted.
Turtles all the way down, yep. At some level you have to rely on heuristics and just make a judgement call, but the checking at the prior levels still has a lot of value.
Straight news reporting has no lower level, short of your going out and talking to the same kind of people the reporter did. Commentary can have such citations. Investigative journalism might have citable passages in part , but ultimately, a lot of journalism is itself a primary source. There's nothing to cite, beyond whatever attribution is given for e.g. quotes in the piece itself (which won't be some hyperlink you…
Think about the NYT example I gave above. How did someone discover that their list of COVID deaths had a murder victim in it? Easy: they read the list, noticed that the 6th person was in his twenties, remembered that COVID doesn't kill such people unless they're already dying of something else and stuck his name into Google. That surfaced another news report about the murder. This is basic fact checking but the NYT didn't do it. The data was too good to check, so they didn't.