I'm not sure this is specifically a Comet Hunter issue. On bright objects getting a starburst is not at all rare in terrestrial photography and I've seen it in astrophotography as well and it's not limited to the Comet Hunter.
More common, of course, if you are using a camera with a camera with an iris without rounded blades and at higher focal ratios so you have a smaller aperture.
But I've not figured out why this is happening with the Comet Hunter/IMX294 combination.
Yes, they are bright stars and reducing the length of your subs might take care of some of the starburst effect.
But the aperture is quite generous so that should not be why you get the starburst. No iris so that shouldn't be an issue. No spider vanes and at least in my example of the OTA I don't have any other obstruction I can identify which should be causing that kind of diffraction.
Yes, there are the mirror clips but the starburst isn't following a pattern I'd expect from mirror clips. There would be three spots of decreased light-gathering and diffraction spiking from three items I'd expect to give either a pattern of 3 or 6 spikes and the images show a lot more than 6 spikes.
We can get diffraction from the sensor itself. The MN34230 sensor is rather famous for it because it has a plate over it which has no anti-reflective coating. But that MN34230 sensor diffraction pattern is different from what is happening here.
I'm wondering if this is an optical/lens phenomenon but I am certainly not going to claim that I know for sure that it is. I'm wondering if somehow the interaction of the wavelength and the refraction through the meniscus/corrector for the Comet Hunter gives this kind of pattern. But again, I do not know enough to be at all confident that this is the case.
I'm hoping someone will give us the definitive answer as to why this occurs - and maybe tell us how to reduce or eliminate it.