Thanks for getting back to me @BrettStokes
In the Survey123 app I draw a shape
I then hit the check mark. If I now use my finger to move around the map (not the shape I drew), the shape shifts location
After submitting the form, the polygon shifts again, the red being what was submitted originally, and the blue being the polygon available for update in the s123 app.
I have only seen this in one survey, but that survey is the only one I use the new-ish polygon functionality so I'm not sure if it's a one-survey issue or a larger problem. I am happy to send you the sheet, but could I send it to an email? I'd prefer not to post it publicly for confidentiality reasons.
Thanks for your help