My guess is that was a VTOL with efficient aerodynamics or jet drone to loiter and power for racing-class activities. If it flies, something like https://fusionflight.com/jetquad/ could pull it off.

Possibilities:

0. Rich, drone expert prankster, or startup showing-off to their buddies/customers "getting away with something" highly-illegal.

1. State actor demonstrating strength, vulnerabilities, and/or doing low-level recon.

2. Terrorists scouting targets and/or probing vulnerabilities.

3. Military demonstrating vulnerabilities for civilian awareness and corrective purposes.*

4. Military seeking budget for anti-drone.*

5. Military-Industrial Complex drumming-up business for anti-drone.*

* Conspiracy theory-ish