I think (or at least I hope) this isn’t true for all of them, but some of the report-producing agencies at the UN are absolutely terrible at their job. Their demographic projections, for example, are a complete joke, and no actual expert in the field has taken them seriously for a while.

Opinions vary on whether this is because of ideological bias or just because a UN analyst job is a sinecure handed out for political favors rather than awarded on merit, but whatever the reason, you can’t at all assume that coming from the UN is a guarantor of quality.