Created attachment 136311 [details] firefox maximized SUMMARY Firefox browser showing wrong title bar button for "restore down" action. STEPS TO REPRODUCE 1. open firefox browser 2. disable title bar through "customize" option 3. maximize firefox window OBSERVED RESULT when maximized firefox is showing wrong title bar button for "restore down" action. EXPECTED RESULT correct button shown for "restore down" action. SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: KDE Frameworks Version: Qt Version: ADDITIONAL INFORMATION
You appear to be using Firefox in client-side decorations mode, which means Firefox itself draws those buttons, not KWin. Therefore the bug is caused by Firefox, not any KDE software. You'll need to report this to them. Thanks!