How to understand configuration about task expired

Summary:

Content (please ensure you mask any confidential information):

Hello everyone,

I would need a clarification regarding the configuration of notifications in journeys.

For our customer we have configured notifications within the task only when the task is assigned and only when it is completed.

What happens when the previous task is expired? Does the second task become completed?

Our customer received a notification in which he sees that task 2 has been completed, but in reality it is not true because task 1 has expired.

Have you ever encountered a similar case? Is there any documentation I can consult?

Many thanks,