In terms of specific reasons to doubt the Gaza Health Ministry numbers specifically, I could go on forever about that, but I don't see the point of doing so on HN. It's not a tech-related question.
With Netanyahu and other far right parties in power I'm not sure this is argument you think it is.
Also not great numbers with the free press either:
Better than some in the region, but not great.
And the refrain gets old when used as a cover for Israels terrible actions, but it actively makes me ill nowadays, maybe not as ill as "IDF is the most moral army in the world" when I think about the tens of thousands of kids they have blown up (killed and injured) I suppose.