I think D+D is short hand for the writers/show runners of the Game of Thrones show, D. B. Weiss and David Benioff, whom everyone blames for the lackluster final seasons and essentially all the issues that came about from adapting books that haven't been written yet into a TV show.

This reddit thread from a couple months ago actually covers some lesser known details about the situation, while D+D certainly deserve some ire for their handling of how the story ended which in turn may have influenced the continued lack of finishing the books it sounds like they're not the only ones who were burned out on the project, especially if they only agreed to 7 seasons under the assurance that the books would be done by the time they got to the end.

I haven't read any of the books yet and only watched the show about a year ago after the second season of House of the Dragon came out, I figured it was time to see what the hype was all about. I can definitely see both why it was the hottest thing on TV for years as well as why everyone was furious at the ending. I can see how all the plot points that got crammed into the final seasons could line up to end the way it did and I can see how it could have been structured differently in a way that could have filled in more of the character development, kept the important plot notes and explained why people did what they did, but I can also see that it would probably have taken another half season or more to tell that much story and without the actual books to fill in the details and actors that were ready to move on, they did what they could with what they had.
They definitely fucked it up, but sometimes there's no good way to end something that's not what it started as.