She’s what you would call Afro-Latina. Somewhere in her ancestry, there is African descent hence why she’s “black .”
I personally think being black is more than just where your great - grandfather was from. Being black is about culture. Something i think cardi would not identify with as much compared to Latin culture. But she’s been throwing the n-word around for so long for brownie points so it’s kind of been brushed under the rug.