Searchengineland:
Google is now sending alerts and notifications from Google Search Console when it detects a “substantial drop” in clicks to your website from the Google search results compared to previous weeks data. Google is basically looking at week-over-week data in the Performance report and if the data is substantially off, Google can send a notification to verified property owners in Search Console of the change.
Google Search Console is now sending out alerts to notify you of any major fluctuations and for those of us who aren’t constantly checking performance reports this is great news. This new feature will make it easier to keep track of performance issues your site may be having so you can fix them faster.