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If I understood you correctly image that send to your Google Spreadsheet is showing error message.
I have cloned form that you provided and I have integrated my form with Google Spreadsheet. After that I made test submission. Image that I uploaded is shown inside on my spreadsheet and I am able to open it.
Did you maybe made some changes on your spreadsheet? Editing spreadsheet can sometime break integration. Can you please try to reintegrate your form with Google spreadsheet to see if that will resolve your issue. Remove current integration and integrate your form again Google Spreadsheet.
Hope this will help. Let us know if you need further assistance.