Fury was lineal Heavyweight champion
He retired last year and vacated the Ring Heavyweight Belt on August 12 2022
When Fury retired Usyk and Joshua were ranked #1 and #2. https://web.archive.org/web/20220817...eightclass=272
They fought and Usyk won on August 20 2022. Usyk also won the Ring Belt Fury vacated.
On October 20 two months later Fury came out of retirement to fight Chisora.
So Fury's "retirement" lasted a little over 2 months.
So when Fury and Usyk fight the true World Heavyweight Champion will be crowned.
The heavyweight lineage is Lewis retires, W. Klitschko reestablishes, and Fury defeats Klitschko. Fury's lineage is unbroken from that point. He has defended his lineal title a total of 9 times.
Fury has retired three times since establishing that new lineage though.