Why did my task move to another day?
Unfinished tasks can move forward on their own – here's how to change that.
Most likely, unfinished-task automation is on. It moves tasks you didn't check off – either to today, or to the same weekday of the next week when a week ends. Sonaa tells you how many tasks it moved each time.
To keep tasks where you put them, open Settings › Tasks › Automation and choose Do nothing.
Recurring tasks and shelf tasks are never moved. More in Unfinished tasks.