Routine tasks that have expired and routine tasks of the day when the completion mark is pressed disappear at the same time.

I have a routine task that I add to my daily to-do list, but it often crosses over into another day. When I press "Show completed tasks" after a day has passed, it deletes the day's tasks in addition to the previous day's. In addition, when I press "Show completed tasks" to restore the day's tasks, for some reason, the day's tasks do not even go to the trash, but are completely hidden (deleted). This problem is extremely serious for me and is not at all what I want from a routine task. Please fix this problem.