What exactly are people referring to when the label this a genocide?

This is The UN Convention on the prevention and punishment of the crime of genocide detailing what constitutes a genocide.

Like, what line was crossed where this changed from defending against terrorists to commiting a genocide, in your opinion?

Here’s South Africa’s 84 page indictment with details and receipts on how the genocide Convention is being violated, assuming a good faith and genuine question on your part.