On: EXIF orientation info in PNGs isn't used for image-orientation: from-image

[lxgr]

JPEG rotation can be lossless for certain image dimensions (multiples of 8 or 16 pixels respectively, depending on chroma subsampling).

I suppose it's no coincidence that the native output format of many sensors (or ISPs, to be precise) is divisible by 16 in both width and height.