Problem with Gantt and shortend previous tasks

Hello, when I move a connected task in the Gantt view, the connected task moves into the future as intended if the previous task takes longer than planned. However, if the duration of the preceding task shortens, the following task is no longer automatically connected to the predecessor task, it just stays there, although it could start earlier, why? Any ideas why this is not working? Many thanks in advance.

Sounds as if your dependencies are set to “Flexible” and not “Strict”.