Another possible explanation (credit to @tinok) is submission editing. Enketo doesn’t modify the start date when editing a submission, but it does modify the end date. Your submissions could’ve been submitted on June 29 but then edited on July 14. Whether or not a submission has been edited can be determined by looking for the presence of <deprecatedID> in the submission XML. To see that, go to https://kf.kobotoolbox.org/api/v2/assets/[your asset uid]/data/[your submission _id].xml.
Example where I made the original submission at 22:07 EDT (02:07 UTC), began editing at 22:12 EDT, and submitted the edit at 22:13 EDT:
Edit: as requested by @wroos, the _submission_time for this instance (looking at an XLS export instead of the table view, due to a time zone bug) is 2022-07-16 02:07:10. How is it exactly the same as <start>? Because I used the “duplicate” feature to create this submission. See my post below for a comparison of <start>, <end>, and _submission_time in an edited, but not cloned, submission.
