If the drones had transponders that could be tracked in the U-space, and there was an ATM model adopted that could track them, then this wouldn't be a mystery. Thales (<a href="https://www.thalesgroup.com/en/worldwide/aerospace/press_release/thales-and-thaicom-establish-foundation-lead-unmanned-traffic" rel="nofollow">https://www.thalesgroup.com/en/worldwide/aerospace/press_rel...</a>) and Airbus (<a href="https://www.airbus.com/en/innovation/autonomous-connected/airbus-unmanned-traffic-management" rel="nofollow">https://www.airbus.com/en/innovation/autonomous-connected/ai...</a>) both say they have a model that tracks drones, even hobby drones.
There's nothing said about what they found on the impact site. The drone leftovers could be telling, at least to find where it came from and who it could belong to?