Yeah, from the other comment I learned that there is a sequence "4d" inserted every 520 bytes, but the ways to retrieve this data are the same for almost all intents and purposes. So is the claim that there is a law that specifically defines that image has to be stored in continuous bytes (without any extra bytes inserted) to be considered CSAM?

(correction, the inserted sequence is "4d0208" in most cases, because it includes the length)

This has nothing to do with laws. It is a malware detection issue because of the contiguous state of the data.