That's not accurate.
Rust is backwards compatible. Most 1.0 code would still compile perfectly fine today. There have been some minor breaking changes for soundness reasons, if I remember correctly. There also has been one edition upgrade (2018 edition), but every new compiler still supports the old edition, and most new stuff actually works in the old edition as well.
There are experimental features, which are only available on the nightly compiler and have to be opted in to with a "#[feature(X)]" attribute. But those are very clearly labelled as experimental, unstable, and evolving, with no stability guarantees whatsoever.
The criticism I would share is that while Rust is backwards compatible, it is obviously not forwards compatible. Rust evolved dramatically since 1.0, and many developers jump on new features once available. So compiling actively maintained projects with a older compiler in distros like Debian is not fun.
But the rate of change has slowed down a lot over the past year or so.