Comment by pornel
It's quite the opposite. The number of high-quality maintained libraries is growing.
Rust keeps growing exponentially, but by Sturgeon's law for every one surviving library you're always going to have 9 crap projects that aren't going to make it. Unfortunately, crates.io sorts by keyword relevance, not by quality or freshness of the library, so whatever you search for, you're going to see 90% of crap.
There was always a chunk of libraries destined for the dustbin, but it wasn't obvious in the early days when all Rust libraries were new. But now Rust has survived long enough to outlive waves of early adopter libraries, and grow pile of obviously dead libraries. The ecosystem is so large that the old part is large too.
https://lib.rs/stats#crate-time-in-dev
Rust is now mainstream, so it's not a dozen libraries made by dedicated early adopters any more. People learning Rust publish their hello world toys, class assignments, their first voxel renderer they call a game engine. Startups drop dozens of libraries for their "ecosystem". Rust also lived through the peak of the cryptocurrency hype, so all these moon-going coins, smart contract VMs and NFTs exchanges now have a graveyard on crates.io.
When you run into dead libraries in Python or Java you don't think these languages are dying, it's just the particular libraries that didn't make it. JavaScript has fads and mass extinctions, and keeps going strong. Rust is old enough that it too has dead libraries, and big enough that it has both a large collection of decade-old libraries, as well as fads and fashions that come and go.