They are published as separate packages, but managed in the same repo by the Deno team. Versioning works fine with JSR.

A fully-formed standard library doesn't spring into existence in a day.

They seem pretty cautious with that unstable flag too.

UUID v7 for example is unstable and one would be pretty confident in that not changing at this stage.

Many unstable functions have less churn than a lot of other “stable” packages. It’s a standard library so it’s the right place to measure twice before cementing it forever.