Careful, you might be looking at the graph of Sample Size in URLs scanned, not total kilobytes. There were more samples because they incorporated a new URL list

Careful, you might be looking at the graph of Sample Size in URLs scanned, not total kilobytes. There were more samples because they incorporated a new URL list around then. There is a size jump, but it is "only" from 1.2Mb to 1.6Mb on mobile around that time.