Hi,
Reading here
support.google.com/webmasters/thread/102...search-results?hl=en
it seems that Google automatically picks on a date displayed on the page.
Checking the page of that product at comprar/bandejas-de-carton I can see that it is the date of a comment on that product.
That's strange it does that since the structured data is valid and it should see that the date is inside one of the reviews on the page and thus ignore it:
validator.schema.org/#url=https%3A%2F%2F...2Fbandejas-de-carton
So I'm not sure what you should do.
I guess the simplest would be to remove the date being displayed on the comments.
In the HikaShop configuration, under the "Features" tab, you have a setting called "Display the date of each comment" which you can turn off to remove the date from the comments listing.