How can I prevent TSR smearing my skybox?

I have a day/night cycle in my game that is simply a giant sphere rotating around with the texture blending between the atmosphere system output and a night sky texture, using no pixel animation. I have been able to narrow down that TSR is causing the stars on the night sky texture to smear as they move. In the screenshot below you can see the blur is introduced around the reprojection step, but fussing with that step’s settings didn’t fix anything. Additionally you can see the transition between night and day creates some very heavy artifacting, again only with TSR enabled. Disabling motion blur doesn’t fix anything, either. Any ideas?