Summing up the article using excerpts from it, but still worth reading in its entirety:

Louisiana v Callais is a major challenge to what remains of the Voting Rights of Act of 1965 (VRA) and could radically rework the structure of political representation in the United States. A successful challenge to the VRA would allow the Republican party to further cheat democracy by engaging in even more partisan gerrymandering and erasing several legislative districts held by Democratic officials, many of whom are racial minorities.

Multiple courts relied on section two of the VRA to strike down a set of legislative maps that did not afford Black voters with equal rights or equal opportunities as white voters. That set off a redistricting process where the Louisiana legislature had to ensure the state’s maps provided Black voters with political representation.

Now the supreme court is being asked to find section two illegal – to say that considering political equality is a kind of discrimination. The argument is that prohibiting legislatures from discriminating against Black voters, by denying them political opportunities, actually discriminates against white voters.