[2023] Play in experimental or wait?

I mean, so far there has been one update to a21, and that update broke player progression because of changes in the update.
This is pretty standard for unstable experimental

You should only play unstable experimental if you are keen to starting over every few days, and want to support the developer by reporting bugs properly.

Originally posted by restarter: any idea when it will go stable?

When it is ready. You'll know when everyone else does.