Professional fireworks are mortar-fired shells, not rockets that can go off-course if nudged. So if a shell hit the drone on the way up, it would smash straight through it and keep on going. There is not enough mass in a drone, and a drone is not solid enough, to deflect the solid mass of a firework shell travelling at speed. It might not quite reach the same height by a few meters, or might end up a couple of feet off target, but neither of these things would matter.
And if the drone is up at altitude where the shells explode, then there is even less speed involved. The shell has reached it's height - so what if it taps a drone before detonating.
There is also whole lot of sky, and both shells and drones are small. The chance of the two coming together is practically nil.
Amazing pictures captured with zero risk. Images from a drone up there amongst it all should be a permanent feature of firework presentations.