The validation of Google product snippets failed, but no errors were detected in Google's structured data test tool.

We received a validation error from the rich product snippet on all products on our website. But there is no error with Google Structured Data Testing Tool.

The validation error is:

"Offer", "review" or "aggregRating" must be specified.

Here is an example of a link https://flagseller.co.nz/teardrop-flags-kitsets/184-custom-small-teardrop-flags-kitset.html