Some sort of lightweight material/string that gets caught up in the blades might work. Use it in flak guns and have it float down to the earth saturating the a

Some sort of lightweight material/string that gets caught up in the blades might work. Use it in flak guns and have it float down to the earth saturating the airspace. You could also use it in a barrage balloon manner. Nets are also a good idea, there has to be a way to physically deny the drones from airspace.