The way people talk about the 3/5s compromise is weird to me. Slaves were still considered property and fully not citizens, it was just how they were counted on the census for the purpose of the House of Representatives (i.e. how many representatives slave states should get). The logical answer, considering slaves had no right to vote, is that the census should not count them as citizens for the purpose of a slave state's representative count, and it was slavers pushing for them to be counted as though they were full citizens in a political power grab that was the problem. It was the positive, rather than negative, side of 3/5, i.e. the present 3/5 and not the absent 2/5, that represented an injustice to slaves. The compromise never should have been made because, for this purpose, they never should have been counted as citizens at all until they were freed, and the compromise strictly gave power to the slavers.

Incidentally, assuming Kamala lived in a free state (which her home state of California was), it wouldn't apply to her at all, she'd just be a normal citizen.