Why would an airport have a beacon light on when there's no traffic?
The Chart Supplement says "Arpt bcn OTS indef."
("Airport Beacon is Out of Service, indefinitely")

It also says "ACTIVATE MIRL Rwy 16–34 and bcn—CTAF"
("Activate the Medium Intensity Runway Lights(MIRL) for Runway 16/34 and the Becaon, by using the CTAF")

Based on this, it is unclear if the beacon is out of service, or pilot-activated.
But it is clear that it should not be on all night.

A phone number is listed on that page for the airport manager, and I might start there.

After that, consider contacting the local Flight Standards District Office (FSDO).