If you're willing to sacrifice search quality for privacy, as in switching from Google to DuckDuckGo, then you might as well take a step further and switch from Google to Searx/Ask.Moe.
Because they have a good privacy policy. They would face legal consequences if they were lying. Nation state actors can presumably override privacy polices but it's better than nothing.
I couldn't figure out which searx instance to use and found no good way of knowing who to trust, most of the engines i used were broken and telling me to find another searx engine.
It looks like it's pulling most of its info from duckduckgo anyway.
Personally I'd rather trust a known entity than an unknown entity anyday, especially when the unknown entity is slow, complicated, buggy and broken in many places.
If you hosted your own instance then it would be a lot more reliable since the IP wouldn’t send a suspiciously high amount of requests.
As for your trust argument, I couldn’t disagree more. You choose to trust DuckDuckGo, who happens to be closed source, because of their branding. The same way people trust/trusted Google/Apple/etc. because of theirs. This thread is a perfect example why being open source is the most important thing for any privacy service (because otherwise this privacy leak likely wouldn’t have been discovered, and people wouldn’t have known that the company so carelessly violate people’s privacy and fail to correct it when people point it out.. it should really make you wonder what’s happening in the search engines codebase).
If you want to market yourself as a champion of privacy, then the absolute minimum criteria should in my opinion be that your codebase is open source.