They will most probably get a slap on the wrist in form of a fine.
List of highest fines: https://dataprivacymanager.net/5-biggest-gdpr-fines-so-far-2...
List of highest fines: https://dataprivacymanager.net/5-biggest-gdpr-fines-so-far-2...
http://fingfx.thomsonreuters.com/gfx/editorcharts/EU-GOOGLE-...
AFAIK, Giving OK to Facebook buying WhatsApp was mostly an Antitrust issue.