For product variants (simple products listed under configurable products) there might be issue with URL links exported to Google Shopping feed.
To fix the issue you need to set simple products to export parent product URL link. To do that please follow the steps below.
1. Set URL link to parent URL export
Click Attributes button.
Click Settings button next to the Link attribute.
2. Set the Filter up
Select Filter button
Select Variants & Types and set Product Variants (Child Products) to Variants only (without Parent products)
Feel free to contact the Koongo support at firstname.lastname@example.org.