In trying to balance quality and file size for various working settings like burst shots or high exposure camera manufacturers came up with what we would call lossy raws: think mRAW and sRAW in Canon or compressed NEF. Even worse is when they don't mention that camera settings like continuous or burst shot or long exposure can downscale your color information to 12 bits.
As
Douglas A. Kerr states in his research after reverse engineering some of the precompressed photo formats with his peers: