Please check tags 0x0106 ("PhotometricInterpretation") in all IFDs:
$ exiftool -H -S -G -a -ee -PhotometricInterpretation IMGP1498.DNG
Here is from a regular DNG file:
[EXIF] 0x0106 PhotometricInterpretation: RGB
[EXIF] 0x0106 PhotometricInterpretation: Color Filter Array
[EXIF] 0x0106 PhotometricInterpretation: YCbCr
Here is from a linear DNG:
[EXIF] 0x0106 PhotometricInterpretation: RGB
[EXIF] 0x0106 PhotometricInterpretation: Linear Raw
[EXIF] 0x0106 PhotometricInterpretation: YCbCr
[EXIF] 0x0106 PhotometricInterpretation: Linear Raw
[EXIF] 0x0106 PhotometricInterpretation: Linear Raw
[EXIF] 0x0106 PhotometricInterpretation: Linear Raw