I assume you have that option unchecked. see screenshot My F11 works just fine. What OS? What Desktop? X11 or Wayland? Try downloading Firefox from Mozilla. Download, unzip, and run '''firefox-bin''' from the folder and see if you have the same issue. https://www.mozilla.org/en-US/firefox/all/#product-desktop-release Operating System: openSUSE Leap 15.6 KDE Plasma Version: 5.27.11 KDE Frameworks Version: 5.115.0 Qt Version: 5.15.12 Kernel Version: 6.4.0-150600.23.78-default (64-bit) Graphics Platform: X11 Processors: 16 × AMD Ryzen 7 PRO 6850HS with Radeon Graphics Memory: 62.1 GiB of RAM Graphics Processor: AMD Radeon Graphics