This is referring to the monotonicity criterion[0]. The page has both toy examples and real world ones. It includes some hints about possible violations in Australia, but your voting system isn't very transparent so it is difficult to audit these situations.
As for vote splitting, I think it would be better to look at Favorite Betrayer[1][2]. Sometimes also called the strong spoiler effect. This is actually a big problem. It is why candidates like Bernie Sanders pledge to not run as independent after losing the primary. If you don't violate this condition such pledges are entirely unnecessary.
[0] https://electowiki.org/wiki/Monotonicity
[1] https://electowiki.org/wiki/Favorite_betrayal_criterion