This increase in traffic are not being seen in the unique visitor counts measured by Compete (https://siteanalytics.compete.com/duckduckgo.com/). It appears as if a loyal core of duckduckgo users are switching to it entirely. Alternatively, duckduckgo users are not tracked by Compete, which is entire possible since I believe Compete gets their data from browser extensions that don't respect privacy. Note, Compete data is old, and wouldn't reflect this surge.