You can read more here:
- https://blog.discourse.org/2023/01/discourse-3-0-is-here/
- https://meta.discourse.org/t/3-0-0-beta15-closing-into-discourse-3-0-with-sidebar-chat-new-menus-and-more/247962
The most noticeable difference is the sidebar, which you can customize yourself by clicking the pencil icon
Or by going to your Preferences > Interface > Sidebar (url https://discuss.eroscripts.com/u/USERNAME/preferences/sidebar
)