via make.wordpress.org => original post link
WordPress 6.1 introduces a new system for managing preferences in block editors. Prior to 6.1, user preferences (like Top toolbar or Fullscreen mode) were only persisted via browser local storage. This resulted in users losing their preferences when they cleared browser data, with their preferences confined to the individual browser instance.
With 6.1, WordPress is adopting a new system for editor preferences. They will be stored server side in user meta in addition to the browser’s local storage. This change means they will now be retained when clearing local storage, and can be used across multiple browsers or computers.
Continuing to use local storage as a secondary way to persist preferences adds a layer of redundancy for situations where a user is offline, or the network request to save preferences in user meta is interrupted.