Creating or editing a task shows the snackbar more than once when navigating

After creating or editing a task, the snackbar displays the message according to the action, but when navigating to a different screen and then returning to tasks screen, the message is shown again.

Reproduce the issue by creating or editing a task, navigating to another screen, and returning to the tasks screen. Trace how the snackbar message is triggered across that navigation flow; done means the action message appears once and does not reappear when returning to tasks.

Written by the indexing model from the issue text.