Exif can also cause confusion for how to render the image: should its rotation be applied or not?

Old decoders and new decoders now could render an image with exif rotation differently since it's an optional chunk that can be ignored, and even for new decoders, the spec lists no decoder recommendations for how to use the exif rotation

It does say "It is recommended that unless a decoder has independent knowledge of the validity of the Exif data, the data should be considered to be of historical value only.", so hopefully the rotation will not be used by renderers, but it's only a vague recommendation, there's no strict "don't rotate the image" which would be the only backwards compatible way

With jpeg's exif, there have also been bugs with the rotation being applied twice, e.g. desktop environment and underlying library both doing it independently