Yes, you are correct. As the SI brochure states: "Compound prefix symbols, i.e. prefix symbols formed by the juxtaposition of two or more prefix symbols, are not permitted."

Unfortunately, almost no one uses SI units and/or prefixes correctly.

Sure, also 1 mAU and 0.5 light seconds, but treating km as a base unit and prefixing it with another k isn't too uncommon a misuse.