Why this issue is happening
The language in which one or more of your products have been submitted to Google differs from the language throughout the headline offer checkout process.
In order to show your CSS product pages on Google, you must submit your product data in a supported language and ensure that the language is the same for your product data and the headline offer checkout page. This includes all the majority of the product data and website pages needed for a user to navigate and make an informed purchase all the way through checkout.
You should’ve received an email asking you to update your product data by a certain date.
Make sure that you use one of the supported languages for CSS Center and that you consistently use the same language across your CSS Center product data and website. Learn more about supported languages.
After you’ve addressed the problem, update your product data and resubmit it using CSS API.