Lennon and McCartney took equal credit for every song, regardless of who actually wrote what. In some cases, it’s come out who the real songwriter was. In this case, there was disagreement.

John Lenon and Paul McCartney split credit for all the songs they wrote during the Beatles, even if the song was primarily or totally written by just one of them. People like to speculate about who wrote what, and after the Beatles broke up both John's would sometimes say who did, but they didn't always agree.

There isn't much significance on the Beatles side of it. On the computer/algorithm/bayesian/tech/math side it might be moderately significant to some.

On the Beatles side, this is one of the few Lennon/McCartney songs where there was any recorded disagreement as to who contributed what. The results of this don't convince me, and given that one of the two involved is no longer here, it won't ever get settled.

It was on the Beatles' Rubber Soul album, released in 1965.