I don’t think the claim is that it’s just committing genocide in Gaza. The claim is that Israel is committing genocide against the Palestinian people because they are Palestinian.
It would be strange to ignore the much larger group of Palestinian people living within territory claimed by Israel in order to say that yes, israel is killing people solely for being Palestinian, but only in this specific little area, and not the other Palestinian people a little ways to the right.
In other words, if Israel is trying to kill people because they are Palestinian, why isn’t Israel bombing the West Bank with the save ferocity as it is Gaza City?
Well the answer is very obvious at least to me: Israel really is targeting the tunnels.