Google has made a data update to the Google Search Console report specifically for mobile apps. The crawl status and crawl errors report was updated on January 23, 2017 to reflect a more accurate "number of app pages with URIs" Google is able to find within your mobile apps via Firebase Google App Indexing.
The data anomalies page says:
Search Console has improved the accuracy of reporting the number of app pages with URIs. This is not a change in the number of actual pages indexed, but rather an accounting change that will show a more accurate number of indexed app pages.
This has zero to do with ranking changes or anything around Google's search results and all about how the report may have changed. Since we have deployed mobile apps for this site, I can share our graphs with you:
My concern is that nothing has changed within the app but now I have a bunch of errors. Before this update, I had about 5,600 URLs indexed and now after I have over 7,000 indexed but about 550 errors as well, as opposed to zero error.
Forum discussion at Twitter.
