Crunchyroll is working with the distribution side of Viz Media because they engage in the same kind of content and both are distributed under Warner Home Video.
Viz Media has their distribution handled through Warner Home Entertainment and Crunchyroll is owned by WarnerMedia through a different company, so they’re like distant cousin companies at this stage.
“VIZ Media, in partnership with Warner Home Entertainment, is responsible for distributing some of the biggest titles in anime.
Viz Media are not controlling these titles in terms of what gets released, what goes on TV, or anything else.