This is a new DebOps stable release, with various bugfixes and enhancements backported from the master branch. Important changes include support for Debian 13 (Trixie) across multiple roles and fixes to Let's Encrypt ACME certificate support.
You can check the changes from the previous release as well as the changes since v3.1.0 release using the GitHub interface. The changelog for the stable-3.1 branch in the HTML format is available on the DebOps documentation website.