via make.wordpress.org => original post link
A new API, known as the “Style Engine”, has been shipped in WordPress 6.1 to provide a single, centralized agent responsible for generating and rendering consistent block supports styles on the client-side and server-side.
For the 6.1 release, the focus has been on consolidating how WordPress generates block supports (border, color, spacing, and typography) and layout styles in the editor and frontend.
Before 6.1, a multitude of instances existed where block supports CSS and class names were compiled and/or enqueued, both in JavaScript and PHP, resulting in a great deal of duplication in both code and frontend output.