I appreciate you for posting your concern here in the QuickBooks Community. I'm here to ensure your concern about finding images from checking deposits in QuickBooks Online is sorted out.
If you're referring to regular checks in QBO, we can find those photos in the Attachment section of the check. Please see this sample screenshot for reference:
Otherwise, if you're pertaining to photos from mobile check deposits, you'll want to check out this article for more details: Use mobile check deposit with QuickBooks Checking. This includes information about where to enter your check for endorsing and submitting.