D has three high quality compiler implementations. It has been around for ages and is very stable and has a proven track record.

Zig has one implementation and constant breaking changes.

D is the far more pragmatic and safer choice for serious projects.

Not that Zig is a bad choice but to say that a unstable lang in active development like Zig would be a better choice for "serious projects" compared to a very well established but less popular lang shows the insanity of hype driven development.