This is the part of the article that cite Jason Barnard:
Does Google use a “trust score” in quality assessments?
If our theory is right, we feel that what is happening with many medical sites that saw drops on June 3, is that Google is giving a low score in terms of trust.
We found this Search Engine Journal article by Jason Barnard really interesting. In it, he claims that Google gives websites a quality score, saying, “the system described in this article is confirmed to be true, but that some conclusions I draw are not (in italics), and that all the numbers here are completely invented by me.”
This “quality score” is made up of many components. Jason made the numbers in this image up, but I think it does a good job at demonstrating how things likely work:
Apparently, each of the factors that Google measures is multiplied together to come up with one final quality score. Most likely, in order to rank well for a YMYL query, you need to reach some kind of threshold score in order for Google to want to rank your site well.