It might be similar to what you found in your tests. Focus at night is not always perfect. For the view downtown at night the maximum I can zoom using auto-focus is 35. When zoom is between 35 and 45 for the view downtown, I have to use manual focus for the camera to lock into focus. I also found that at night auto-focus zoom is about 80 percent accurate using the presets. That is about 20 percent of the time focus will be slightly off. In this case I have to back off the zoom a fraction for it to focus. In the video above you'll notice that the wide view that begins at the 56 second mark (zoom 23) the camera is slightly out of focus. For the streets directly below our house the auto-focus works to the 45 zoom level, but at times it is a little slow to focus.
After using this camera for a while now, I'm happy with the night time color. I've tried several other cameras, including a 4MP 30x PTZ, and 2 different 4K cameras. This camera still has the best image at night in color. For best daytime image, the 4K cameras are better. The 4MP 30x PTZ is not as good as 4K, but still better than this camera for daytime image. Here is a frame capture from last night.