There's not a lot of genocides that are entirely ignored historically speaking. Loads of nations who deny them, and use propaganda machines to spread disinformation about them, but global scale denial is not really possible.

Genocidal acts are not dependent on the scale of those actions. What matters is the acts themselves and the intent behind them. The context of the situation in which those actions occur is also a consideration. But we recognize thousands of genocides throughout modern history. The Armenian Genocide is the progenitor of modern conceptions of Genocide, but the term is retroactively applied to lots of historical cases of ethnic cleansing.

The actions Israel is taking are and have been genocidal. This situation is not new. Israel has massacred Palestinians en mass for nearly 80 years. They are taking systematic actions to kill Palestinians, to disrupt their way of life, to destroy their culture, to grass their history, to steal their land and their homes, to mass incarcerate them, to mass sterilize them, to forcefully relocate them, and to cause mass scale healthcare emergencies by way of starvation and dehydration under prolonged siege and blockade. These are all very common actions under imperialist colonial regimes.

This is a genocide. The only reason there is pushback on that is because the nation in question is Israel. If this happened elsewhere in the middle east there would be 0 hesitation to label it as genocide. The existence of a terrorist organization does not provide justification for genocide and ethnic cleansing.