I have two packs that look identical, one says 1300mAh 95c and the other days 1800mAh 55c. Same weight, same size.
Interestingly, they really are about the rated capacity.
Battery volume can be used for C or mAh, but not exactly both. The 45c definitely seem to be higher C, but that makes sense that it comes at the cost is more weight for s given mAh.
I doubt they’re 45c OR 260mAh of course, nor are the 260mAh 30c likely to be either thing, but higher C on a given mAh will weigh more just like more mAh at a given c will.