You may have noticed the forum looks a little different today - the latest update to Discourse (the forum framework) has dropped support for the old style layout and moved to the new Sidebar format that was first offered in Sept 2022. We wanted to give the feature time to mature, and we’ve now hit the point where it is required to stay up to date with the latest bugfixes and security patches to Discourse.
You can read more about the changes here: New Sidebar announcement on the Discourse forum
To summarize:
The new sidebar lets you customize your navigation so you can get to your favorite parts of your community, and the new notifications menu that lets you more easily decide which of your notifications deserve your attention now and which ones can be dismissed or be saved for later.