The tab button is an extremely useful way for desktop users to navigate UI elements in the world. With Tab bound to free-look, it is impossible to interact with UI elements other than when the head is in the way.

( See also: https://feedback.vrchat.com/third-person-view/p/using-tab-to-navigate-ui-is-not-accurate-in-third-person )

There are some worlds where holding Tab brings up a world menu that fills the screen. This is useful UX in my opinion because the menu can be brought up from anywhere and automatically navigated easily due to the tab-ui-navigation feature.

I agree with a suggestion from the discord to switch this to the middle mouse button because it synergizes well with the existing camera controls (move/zoom) and is consistent with the desktop controls for the picture camera.