Google can penalize your website if you use event markup in a misleading manner.
Google is warning publishers and webmasters not to use event markup in a way that is misleading to searchers, or else Google will remove the ability for your whole website to show rich snippets in its search results.
Google said it has recently updated and clarified the guidelines around the use of event markup after they received a lot of feedback around the misuse of that markup. Specifically, Google is calling out publishers in the coupons/vouchers space as marking up their offers with event markup. “Using Event markup to describe something that is not an event creates a bad user experience, by triggering a rich result for something that will happen at a particular time, despite no actual event being present,” Google wrote.
Here is an example of such misleading rich snippets:
If you do this, Google said it “may take manual action in such cases.” A manual action is when a human at Google marks your website as doing something against the Google guidelines. Normally, it results in ranking demotion or delisting but “it can result in structured data markup for the whole site not being used for search results,” Google wrote.
If your site gets one of these manual actions, you will find a notification in your Search Console account. From there, you can take corrective action and submit a reconsideration request.
Google has been penalizing for spammy structured markup for a few years now, but clearly, Google is going to step up action around event markup spam soon.