Didn’t the gh5s already do that? What the she has going for it is video codecs, but then the gh5s improves video quality even more...

Usually it’s because of limited pixel readout rate or limited processing rate. 4K(UHD) video is only 8MP, ideally it would scan the whole 12MP for every frame, but that would require 50% faster pixelrate (megapixels/sec). It would also mean 12MP frames would have to get downscaled to 8MP (UHD) in realtime. On top…