Nothing is bent, Tom. There is no fisheye effect turned on.
There is clearly something screwy with the FOV. When you pan to the left and right it looks like the moon and sun are warping around an inverted sphere.
Why is it that in your original video that you had to "zoom in" after
this scene to get the desired effect rather than simply place your camera closer to the moon? Simply placing your camera next to the moon would be the simplest thing to do, and would more accurately represent the earth-sun-moon system.
Whatever you did there with the FOV is clearly unnatural. In the beforehand scene we clearly see that the moon is pointing at the sun, which I illustrated with a red line. If you take a magnifying glass to the moon in
my image and follow the path to the sun it clearly makes a straight line.
We don't have zoom-in pincushion eyesight, or whatever inexplicable thing you did there to achieve your effect, so why are you trying to pass it off as reality?