Actually, to be clear, it is not FDD that is conflating the Hams and IDF numbers, but the Persian Jewess Twitter feed itself.
But the agenda of the FDD also seems clear in its implication of the US media acting irresponsibly when they say, “On October 16, the health ministry told global media that an Israeli airstrike was responsible for an explosion that killed 500 Palestinians at the Al Ahli Arab Hospital in northern Gaza. U.S. media quickly reported the story even though it became clear within hours there was no evidence to support claims of an airstrike or a death toll close to 500”, when in the link to CNN in the sentence you can see the lead line is, “More than 500 dead following strike on hospital in Gaza, Hamas says” (emphasis mine). So they are imputing a pro-Palestinian agenda among the US media even as they follow standard established journalism ethics, and they are using the Bari Weiss Free Press, a pro-Israeli opinion site, to dispute the claims.