Historically, say, 15 years ago before 1.0, Rust too was always shifting about and so you'd find that the software you wrote last month now doesn't even compile and the advice has changed.

Today most people write entirely stable† Rust, and as somebody else mentioned Rust uses Editions to allow it to make any remaining language improvements, but if you were writing mostly unstable Rust you would see a reduced version of the same churn. Last month you could foozle.boozle() and that gets you a Wibble, but then you upgraded and now foozle doesn't have a boozle method, and apparently Wibbles no longer exist at all, everybody says you need to learn about Wumps instead now because those are apparently better or something?

† If you don't use a "nightly" build of Rust or a special opt-in "nightly mode" your Rust compiler only recognises the stable language.

It might not be the version you have installed, or the same version as another project you want to glue together into a single application.

Rust has editions, which can be mixed and matched between different dependencies. AFAIK Zig does not have this.