Attacking Harris because she's apparently "not black" is so idiotic. She went to Howard.
The more effective play would be to not reference race at all. The second most effective would be (if you're going to venture into race) hammer the "DEI" stuff. It hits the notes the base likes, and it's at least like, not obviously disprovable merely by looking at her. And it's still the hyper aggressive, arguably racist crap the right craves right now. That's what Meatball would've done, and I think it'd be quite a bit more effective than the current play.
"She's not black" is just confusing because like, she's a black lady and she looks like a black lady.