It's not so much "authority" but "trust" that has gone down.
There used to be institutions that were regarded as the gold standard for truth: the FDA, top science journals, the CDC, the Bureau of Labor Statistics, and so on.
These weren't necessarily regarded as infallible. But it was widely recognized that they undertook a best effort to get at the truth, and would tend to err on the side of caution.
That trust is falling apart. Many people, including in the HN community, cheer this decline. They see it, not entirely unreasonable, as the downfall of despised "elites" and opening the discourse to other voices, making it more democratic.
But while the tearing down of institutions is well ahead, there is little indication that the envisioned surge of bottom-up publishing is anywhere as successful: almost no structures have appeared, for example, that provide the nitty-gritty coverage of local politics.
Nor can I think of any actual corruption by these organisations exposed by amateur sleuths. Even Snowden relied on traditional media to get his message out. Just today, the Seattle Times (old media) revealed their investigation of the broken process of Boeing's certification of the 737 Max.
"Critical thinking" is what's usually recommended in these times of information overload and bad actors. But the term just seems to give license to everyone to make up their own facts as needed. The result is a discourse devoid of agreed-upon facts. If you cite inflation data in economic discussions, the most likely reply is a conspiracy theory about the data being corruptly influenced. "Think critically", they say, "who profits from , I bet they get a big fat payoff from for telling this lie".