Why do investigate findings get half credit?
Because an unproven signal is not the same as a proven failure. A canonical pointing at another domain is either correct syndication or a serious mistake, and nothing visible on the page says which. Scoring it as a pass would hide it. Scoring it as a failure would punish sites doing it right.
Reading The Results
Answer it for your own page
The inspection is free, needs no account, and takes a few seconds. It reports what is actually wrong with a page rather than what is generally true about pages.