Steps to reproduce:
Open one window. Notice that the small window indicator is absent.
Open another one. The window indicator appears.
Close one window. The small window indicator stays, even though this state is identical to line #1.
It only goes back to #1 when you restart Orion. Closing all windows and re-opening yields #3.
The small window indicator disappears when there is just one window.
Orion and macOS:
macOS Version 12.0.1
Orion Version 0.99.109.1.1-beta (WebKit 613.1.12)