If anything this shows how pangram is unreliable. Chances are, if someone is running an article generation thing, it'll be 100% generated. Writing 3 / 100 articles "by hand" doesn't make any sense.

They do seem to have an internal review process, some articles might have been heavily edited, particularly early in the development process.

But indeed, if Pangram is marketing itself as "near-zero false-positives" now, that entails that the are aggressively biasing it towards being conservative, likely leading to lots of false-negatives and low match scores on AI content.