So again, please provide a source! I can't find one.
It's clear that DuckDuckGo used Bing for some result, but not to what extend. Are all result Bing? Does Bing only provide results when DuckDuckGos own crawler fails? Are the results mixed? I very much get the impression that results are mixed, but that's not completely clear either.
Their own crawler is only used for fluff like widgets. All organic search results are from Bing and Oath:
> In fact, DuckDuckGo gets its results from over four hundred sources. These include hundreds of vertical sources delivering niche Instant Answers, DuckDuckBot (our crawler) and crowd-sourced sites (like Wikipedia, stored in our answer indexes). We also of course have more traditional links in the search results, which we also source from a variety of partners, including Oath (formerly Yahoo) and Bing.
I've seen the ddg bot in my home webserver (with a .com) logs in the past month. I even bothered to check to make sure it's IP matched the ones on the bot about page.