Nós means "we" so he's saying she called her family that.
And "neguinho" is a hard translation because there isn't a perfect equivalent in english. It's true that it can be used affectionately (many couples call each other meu preto/neguinho as pet names), but that's
not the way Piquet used it.
It translates to "little black (person)", and it can be a substitute for "someone" too (talking about an unspecific person - and even this use of it is questionable to me), but when you put the "o" in front of it the meaning becomes about a specific person and you are choosing to refer to them by their skin color (and in the context of the video he is criticizing Lewis, so he is doing it in a negative and racist way. It also matters that when talking about Max and Senna in that video he uses their names, so he's making an active choice to not use Lewis' name but that term instead).
I think in this caption Rodrigo is trying to take advantage of the other meanings the word can have to convince people Piquet didn't mean it maliciously/with racism, but looking at the uproar this has caused in brazilian twitter you can see that's not true. He has now made his account private because of the backlash from this post too.
Yes, if you look in CNN Brazil's page there are over a thousand comments, all siding with Lewis. Piquet's close relationship with Bolsonaro and the many disgusting things he's said about other drivers really soured his image to many (this was mentioned earlier in the thread, he talked
tit about other driver's wives, created rumours about Senna's sexuality. Disgusting man all around
). He has the same amount of championships as Senna, but will never be as loved as him and he knows it. And seeing his country love and support Lewis more than him upsets him the most.