It’s the curse of popularity!
As soon as gaming a search engine becomes financially profitable, the hoards of “SEO”s develop methods to do so.
On plus side, this means ddg is finally getting noticed, on the minus side, this means they need to react fast or lose ground to the competition that’s relatively better able to fend off spam.
Btw, this is also why search engines only grow big (or go home). Fending off spam is very very expensive and thankless job!