This was at the Tijuana airport which is right next to the US border. While drones have been know to be used to smuggle contraband across the border, looking at this flight path for landing [1], the plane actually circles around over the US and then back into Mexico. It's possibly that the the strike occurred in US airspace. yikes

Note: I'm not certain that this is the flight in question. The other approach is solely in Mexico airspace. I'm also not trying to rope in drones/contraband to an already unclear situation.

[1] https://flightaware.com/live/flight/AMX770/history/20181213/...