My absolute guess is it comes from the Digital Chart Supplement data published here[1]. Notably this supplement does not contain things like airspace boundaries, airways, obstructions, and so on which would be required to produce a useful sectional chart. This is more like the kind of data that you'd use to print your own Airport Facility Directory.

1: https://www.faa.gov/air_traffic/flight_info/aeronav/digital_...