Coppola said that Paramount were unprepared for how successful the film would be, and as such, played the same reel over and over again instead of preserving the original negative the film was projected on. Mockoski added that for the 2022 restoration, they worked from a restoration by cinematographer Gordon Willis, but even that process was fraught with difficulty.
Source: ‘I was just glad to have survived’ – Francis Ford Coppolla reflects on making ‘The Godfather’