I just ran half a dozen identical searches on DDG and Bing, and yeah it looks like DDG is returning the same main results as Bing (if you ignore all the AI stuff at the top of Bing searches).

Could be, but I don't think so, because I use Ecosia, which is even more of a Bing skin than DDG. DDG adds some of their own flair into the mix, but Ecosia is pretty much just Bing I believe. In any case I don't feel like I'm getting much in the way of AI spam. For the few searches I do try on Google, I think it's safe to say that Ecosia/Bing is now a better search engine that Google.

Realistically I think it has more to do with the terms your searching for, and not necessarily if one search engine is worse hit by spam, AI or otherwise.