Release numbering - beta verus non

I’m a little confused by the release numbering. The current beta is 4.2.0877 but the production release is 4.1.0879, and appears to have fixes not in the beta.

It used to be that production releases were only made available after betas were thoroughly tested, and included everything from the beta. A new beta “branch” was then created.

Is that no longer the case?