The 80% figure bundles two different things. Only one of them closes with Malacca.
Gulf crude exits Hormuz before transiting Malacca - two sequential chokepoints on the same cargo. West African and Americas VLCCs round the Cape of Good Hope and reach China via Lombok, a separate chokepoint with no Malacca exposure. Russian ESPO loads at Kozmino and crosses the Pacific: no maritime chokepoint at all. The structural Malacca dependency is 55.8%, not 80%. Hover any node or flow for detail.