Sean Connery quickly became synonymous with the James Bond franchise, but his 1971 entry into the film series was arguably the beginning of when Bond continuity started to become very confusing. Connery is tied with Roger Moore for appearances as the famous spy, but an asterisk next to one of Connery's Bond films arguably hands the title to his competitor. Despite originating the role, Sean Connery's time spent as James Bond is a little more nebulous than most, and so the franchise's continuity takes a hit as a result.

https://screenrant.com/james-bond-canon-confusion-sean-connery-thunderball-book/