Which of course depending on their ranking implementation seems kinda odd, as you could expect a big part of the users of SO also to be the ones using DDG. But again if it categorically undervalues results from there, then those users will of course find alternatives.
Might be the query then, I usually get the proper SO result as one of the first 3 matches. Anyway if you're getting results that are really off, hit the 'Send feedback' button. A DDG employee here on HN claimed they use this actively to make results better - hard to teel if that is so, of course.
This is what I've noticed as well. Searching for Rust programming questions is very hard with DDG, whereas Google gets relevant results at the top. Otherwise, DDG and Google are pretty much on par.
The only downside is the quality of results.
Most of the time when searaching technical questions I get better results on google compared to ddg.
It looks like ddg doesn't like stackoverflow.