His cancer battle had been widely known for years and in 2016 we learned that he sued The Roots:

"In 2007, Hubbard was diagnosed with multiple myeloma, a type of cancer, forcing him to leave the group, according to his lawsuit... He also says the band's manager threatened to cut him off from all payments and health insurance."

https://www.courthousenews.com/ex-roots-bassist-sues-for-removal-from-ventures/#:~:text=In%202007%2C%20Hubbard%20was%20diagnosed,excluded%20him%20as%20an%20owner.