Rust is not a Mozilla project, but it is sponsored by Mozilla. https://research.mozilla.org/rust/

Interesting, I thought that Rust was a Mozilla project because the Wikipedia page listed it as its developer. https://en.wikipedia.org/wiki/Rust_(programming_language)

Mozilla was heavily involved in the early development of Rust (and since there is no Rust Foundation, is the holder of the Rust trademarks etc.).

But at this point however you can't really call it a Mozilla project as active development is no longer dominated by Mozilla employees. Holding the trademark is just a formality owing to there not being a better way to do that without starting up a new Foundation.

> Mozilla chose Matrix but they advertise Slack on the linked page.

Gotcha, I missed this. Very odd.

> Is Rust not a project of mozilla?

Mozilla was the first sponsor of the project, and still sponsors a bunch of stuff to this day. But they don't own the project, and cannot make decisions on its behalf.