Re: "I heard you have a dragon problem?"
Well, nitpicking the physics of a technique that makes a mockery of physics is kind of an odd thing to do. But I guess I see the validity of the criticism.
The way I imagine it is that, while the force of the recoil is big enough to break Starlow's telekinetic hold on the gun, her grip does not break "evenly". If we assume that her hold breaks first on the front, you'd get a similar result as when you're physically pushing against the recoil, i.e. an upward motion. If we combine this with the fact that the gun is still transitioning back to its original, gravity-affected state from a state of extreme floatiness (the telekinesis makes it floaty) and had not yet entirely finished that transition at the moment of the shot, temporary weird moon physics are not unlikely.
I do admit the arc is kiiiind of exaggerated, though. I mainly did that for effect without much regard for physical accuracy. Like, I thought as long as the general idea is clear, I could get away with forcing the spectacle a little.
There's also been a different logic error I made during the update, and I focussed on correcting that one over the physics
one.
But if it bothers you, I can redraw the panel to emphasize the backward motion over the upward motion.