After upgrading my Firefox to version 145, a blue line appears at the top of the browser window when it's in full-screen mode and the current window is focused. I know this is to remind the browser window that it's currently focused and interactive, but I really hate this notification and want to make this conspicuous blue line at the top of the window disappear. I couldn't find a relevant option in the Firefox browser settings. Does anyone know how to set this up?

Please help me to disable this focus tip,thanks!