I did a search on “niggard,” the noun form that sounds more like the racial slur. I got 65 hits. The word has never been used in casual conversation on this board. It shows up in discussions like this one, and in quotes from Shakespeare, Pound, and Tolkien. That’s it. “Niggardly” gets 654 hits (about 50 of them this week), so I’m not going to look back over all those. But I did find one legit usage and it’s from only three months ago.
So we can say it happened once, but it’s used in discussions of the controversy way more than it’s used on its own.