While the image itself does not seem to amount to much, the accompanying EXIF data points to an original resolution of 5,312×2,988 pixels, which has a 16:9 aspect ratio – which would end up with a 21MP camera instead. Just how does one arrive at this particular conclusion? Well, photo sensors in smartphones feature a 4:3 aspect ratio, which means the highest resolution 16:9 photo that one can capture in reality is of lower resolution compared to the highest resolution photo one is able to take. A 16:9 shot like the one which was leaked would use the full width of the sensor only, but not the entire height. When you extrapolate that figure, it would result in a 5,312×2,988 resolution.
Do bear in mind that it is a snap to fake EXIF data, so do take this with a grain of salt.