At least the Chrome team is still oxidizing.

I mean, they are, so presumably you mean more quickly ? There's a HN article about this after Mozilla fired loads of Rust hackers, and a larger fraction of the Firefox codebase is in Rust than was then, which was in turn more than in 2021 when I first was interested.

It's possible that if Rust had remained "secret sauce" for Mozilla it would have hurt its usage elsewhere, impossible at this distance in time to be sure. There is, for example, far less Rust in Chromium (less than 4%) than in Firefox (more than 12%).

Clearly, the fact that Servo failed must be indicative of shortcomings in Mozilla itself, and not Rust the language, its ecosystem, or its users.