That's just factually wrong. The only racial distinction made in the the clause is the exemption for un-taxed Indians. The 3/5 only applies to Non-free individuals. A Free Black Man was counted as a whole. An enslaved black person was counted as 3/5, but ONLY within the context of assessing the number of representatives to congress.

The theory is this: Slave Owners wanted to include the Slave population so they could have more representatives, and more power in the congress.

Abolitionists wanted to not include the Slave population, because those Slaves could not vote for those representatives, and therefore the representatives would not be representing the Slaves.

Saying blacks were only considered 3/5 of a person is completely wrong.

Saying black SLAVES were only considered 3/5 of a person is only half right.

Saying citizens from slave states used slaves populations to make their ballots count more than than citizens from free states is correct.