Something let go. First Karma was high enough that bird shot would be pretty ineffective I think. (Have done a little bird hunting.)
Second the quivering in the video was not the drone being scared shitless because it saw something coming, but was caused by something happening in an arm or motor or blade. Hard to tell. Should be able to tell by what was recovered.
Agreed, look way too high for a shotgun and you'd have to be a sniper to hit that small of a (moving) target that high up with a rifle...
Which then begs the question, was it a catastrophic failure or a bird? This time of year - at least on the East Coast - mama birds are very aggressive towards other birds (drones?) to protect their babies