The purpose of a Beta is to collect feedback on an image before it is released to GA. The goal of a Beta is to identify and fix any potential issues that exist on that image. Images are updated on a weekly cadence. Any workflows that run on a beta image do not fall under the customer SLA in place for Actions.
Customers choosing to use Beta images are encouraged to provide feedback in the runner-images repo by creating an issue.
macOS 13 is available in GitHub-hosted runners since 2023-04-24.
At the time of writing, it's still considered beta, and
macos-latest
uses macOS 12.Related: https://github.com/exercism/configlet/issues/661
Their defintion of beta: