Not 100% yet which versions are affected but we're currently crosswalking out too many dates to citation_date:
google.citation_date = dc.date.copyright | dc.date.issued | dc.date.available | dc.date.accessioned
This patterns is "first match", so in case dc.date.copyright isn't filled out, dc.date.issued is consulted, after that the automatically generated deposit dates are offered.
The consequence is that sometimes, the date submitted into the repository gets exposed into citation_date. This makes it hard/problematic for Scholar to match it accurately against the actual publication date for the item.
If there is no accurate publication date, no date should be crosswalked at all. So I propose ONLY crosswalking dc.date.issued by default and remove the fallback options we have today.
Quick Fix (for any site running DSpace 1.7.x or above): Modify your [dspace]/config/crosswalks/google-metadata.properties configuration file. Change the "google.citation_date" setting to ONLY list "dc.date.issued".
google.citation_date = dc.date.issued