"Truth" is often a very expensive commodity to obtain. There are plenty of awful sources and mistaken claims on the shelf of any town library. Lots of peer reviewed papers are crap, including a few in Nature. Newspapers are constantly wrong and misleading. Digging through even "reliable" sources can require significant expertise. (This is, in fact, a significant part of PhD training, according to the PhDs and professors I know: Learning to use the literature well.)
One way to successfully use LLMs is to do the initial research legwork. Run the 40 Google searches and follow links. Evaluate sources according to some criteria. Summarize. And then give the human a list of links to follow.
You quickly learn to see patterns. Sonnet will happily give a genuinely useful rule of thumb, phrasing it like it's widely accepted. But the source will turn out to be "one guy on a forum."
There are other tricks that work well. Have the LLM write an initial overview with sources. Tell it strictly limit itself to information in the sources, etc. Then hand the report off to a fresh LLM and tell it to carefully check each citation in the report, removing unsourced information. Then have the human review the output, following links.
None of this will get you guaranteed truth. But if you know what you're doing, it can often give you a better starting point than Wikipedia or anything on the first two pages of Google Search results. Accurate information is genuinely hard to get, and it always has been.