EpicFlight
Well-Known Member
The reason for this, IIRC, is because the 1 has a less capable video processing pipeline, and can't handle the 4K data rate.The mini 1 uses line skipping and pixel binning to record video from a larger higher resolution sensor area at a lower resolution. This is very common practice and is the same method used to record even lower resolution video, such as 1080p, with the same field of view.
The line skipping and pixel binning could also account for the noticeable loss in detail as well as the aliasing noticed by @Kilrah compared to the Mini 2.
Sensor pixel resolution isn't the only important factor here, by far.