Not every requirement is a requirement
A job posting is a wish list with a few hard filters buried in it. "Strong experience with Java" and "exposure to Kubernetes is a plus" are not the same requirement, and treating them as equivalent is why people either over-prepare for a nice-to-have or fail to notice the one thing they genuinely need.
So this tool sorts what it finds by how hard the posting asks. Must-have covers what was stated as a requirement. Preferred covers what was named as a plus, a bonus or a nice-to-have. Mentioned covers everything present without a stated level of importance - worth knowing, not worth reorganising your preparation around.