History of changes
When you modify your checklist, each change will be visible in the issue history. Changes are visible in batches - every time you modify something and then click Save, it creates a new batch of changes in issue history.
If you check and uncheck the same item many times before saving, the history will show this action only once. If the change was done less than 1 minute ago from the previous one, then a new change will be added to the batch. If after - a new history note will be created.