Search Console experienced a data outage that ceased on April 26. The outage affected all reports except the Performance report. All missing data from April 9-25 was replaced with the data from April 26, when data began to be available again.Google post on Data Anomalies Page
What does it mean for your website and what to do with it?
First of all, you should not take into consideration any data from 9th to 25th of April in any Google service not only Google Search Console. The thing is that the data loss was due to algorithm bug which may affect data in Google Analytics, Google Ads, Google My Business.
Secondly, this bug may have caused de-indexing of some of your pages. So you better review your pages indexing status and request indexing.
Thirdly, backlink report on Search Console is not recovered yet which means that the bug might not be fully resolved yet. Therefore don’t take any data too critical for the next couple of weeks.