The Constitution’s original three-fifths compromise was that, for the purpose of representation in the House of Representatives, slaves counted as three-fifths a person. The South obviously wanted it to count as five-fifths because that would give them even more representative power by people who weren’t allowed to vote and the northern states wanted it counted as zero-fifths. The compromise was that each slave counted as three-fifths of a person who couldn’t vote.
Prison gerrymandering is arguably worse because people in prison – like the slaves – can’t vote but they count as an entire person. So they have even more electoral weight with the same lack of voice. And I used a five-fifths compromise on purpose because there’s a clear racial component to this.