It has a 2-part process. First, it does a simple depencency check against Google's OSV, then there's a supply chain check that requires an AI key. This secondary check uses code signature checks to identify files that have "risky" behavior (e.g. eval, lots of encoded code etc) and passes that to an AI to identify whether it's likely malicious code hidden behind the "risky" behavior.

Disclaimer: I work on this project.