DDG is based in the US, therefore it is entirely possible that they have been ordered to keep logs and track everything the users do on that site with a gag order.
Being based in the US is a dealbreaker for privacy.
I'm not sure I got the grammar right, but - being based where isn't a deal breaker for privacy? Any government might compel a business to do stuff and to keep quiet about it. The fact that the US actually did it kinda suggests that, I dunno, Russia or China are certainly doing it. Note as well that the US or another powerful state can compel a smaller state to do things to businesses based there, and keep quiet about it. So even if you trust some state more than you trust the US when it comes to secretly doing things that you don't like, you'd need to also count on it to be able to say "no" to the US as well as other powerful states... good luck with that.
If you want your searches to not be used for targeted advertising, DDG sounds like a sensible option, actually. If you don't want governments to know what you're searching for, that sounds really hard to strongly guarantee. (I'd think they're logging your communication way before it reaches the server, in particular.)
It is certainly more difficult for US and other powerful countries to enforce its diktat on certain countries (like those in Europe). They are more powerful in a geo-political sense and also have a deep-seated fear of government surveillance.
You're simply trading one governments surveillance for another. The US isn't the only government conducting advanced surveillance.
Being based in the US is a dealbreaker because of US Surveillance.
Being based in the Canada is a dealbreaker because of Canadian/US/UK/Austrailain/New Zealand Surveillance.
Being based in the France is a dealbreaker because of French Surveillance.
Being based in the Germany is a dealbreaker because of German Surveillance.
Being based in the Japan is a dealbreaker because of Japanese Surveillance.
Being based in the Austrailia is a dealbreaker because of Canadian/US/UK/Austrailain/New Zealand Surveillance.
Being based in the Spain is a dealbreaker because of Spanish Surveillance.
The question is again, where exactly is government survailence not a deal breaker? Every country that is capable of it is doing it, and every country that is not capable has agreements with those that do.
US surveillance isn't limited to the US; the NSA spies on everything, its just that it's spying within the US is controversial given that it's legal mission is foreign signals intelligence, and the US has statutory and Constitutional limits on domestic government surveillance which are arguably violated by the NSA's domestic surveillance. NSA engaging in universal and total foreign surveillance is far less controversial in the US, but it would be a mistake to conflate the lack of controversy with a lack of NSA activity.
Also consider corporate 'surveillance'. Google tracks more than the surveillance state asks from them. Same with Facebook. And that's just so our ads can be targeted. But folks flock to those platforms. Because they can do business there. People are not as picky as we'd like to think.
And that's why it makes no sense to use DDG if you are paranoiac. If you use DDG because you think promoting websites that "Seems" to put privacy in front, then that's a good thing. But if you are really paranoiac, then just use proxy/VPN with google.
Being based in the US is a dealbreaker for privacy.