How Did Black Panther Die in the MCU?

While many Marvel heroes die heroically in the battle with the enemy (for example, Black Widow and Iron Man against Thanos), some may have a much more quiet death. In 2020, Marvel leaker Mikey Sutton revealed to Geekosity:

“T’Challa’s passing will reflect the sad reality of how Boseman died, from a disease. Whether this is cancer or not, I am not currently aware but that seems to be the likely scenario, a way of honoring the actor, and acknowledging that everyone, even superheroes, can succumb to a real-life illness.”