This is the discussion that led to the opening sentence of the article being changed: https://en.wikipedia.org/wiki/Talk:Gaza_genocide/Archive_12#...

As you can see, it wasn't just a few editors saying, "lol, let's just say it's a genocide." Hundreds of people weighed in on the proposal. They looked at lists of recent sources.

There were previous discussions like this that came to a different conclusion. But as more and more sources started calling it a genocide, Wikipedia editors eventually decided the opening sentence had to be changed.