You're right, the difference between the selected level tab and the other tabs is actually less visible under Windows 11 (right in the following image) than under Windows 10 (left). I note this and will try to improve it in a future version.

when right clicking on the levels pane I would expect to just get the popup menu window, but it also causes to make the level the cursor happens to be on active

This right click behaves quite weirdly. Sometimes it selects a tab, sometimes not. I will try to fix that too.