I've yet to see that come up as an issue within this niche - it's mostly code based work, so a certain tolerance for forking/remixing is baked in. Unsurprisingly, highly derivative work doesn't raise much interest.
I'm deep in the generative art NFT thing too, and I've seen it come up a couple of times.
In a couple of cases algorithms have been outright copied and used for new projects. Personally I believe that's wrong and people shouldn't do it. Definitely would not buy any such work.
There's also been a few cases where some code is clearly based on other code, and some artists get mad about that. For myself, this feels a lot less clear cut, and I might consider some such art if I felt it was novel enough.
Sure, but you probably weren't trying to sell those copies to unsuspecting buyers, pretending you had the rights to do so, and giving nothing to the artist. That's the scummy part.