In what possible world is Hamas this careful entity that's concerned about their credibility and standing on the world stage
Along with Likud, Hamas is one of the primary entities ensuring the continuation of the decades-long slow genocide of the Palestinians. That's why Likud has historically given them so much aid and support. They're two peas in their own little murder-pact pod, and millions are starving or dead now as a result.
(Edit: My criticism of Hamas doesn't mean I'm criticizing the effort the Gaza Health Ministry puts into getting good and accurate numbers. This article touches on at least a little bit of where the undercount in their figures might come from, despite how hard they're trying to report accurate numbers. Among other things, it says that 30,000 is only the estimate of people directly killed by the IDF, not anyone who dies of starvation, disease, or injury. Maybe that's part of the difference, or maybe Nader is simply throwing ballparked numbers around without nearly as much rigor as they put into it.)