Why do they just mention absolute numbers, instead of comparing them to similar platforms? All they said was that there is CSAM on the Fediverse, but that's also true for centralized services and the internet as a whole. The important question is whether there is more or less CSAM on the Fediverse, no?
This makes it look very unscientific to me. The Fediverse might have a CSAM problem, but you wouldn't know it from this study.