My experience is that all LLMs that I have tested so far did a very good job producing D code.

I actually think that the average D code produced has been superior to the code produced for the C++ problems I tested. This may be an outlier (the problems are quite different), but the quality issues I saw on the C++ side came partially from the ease in which the language enables incompatible use of different features to achieve similar goals (e.g. smart_ptr s new/delete).