You appear to be using the old Firefox 121.0 when you need Firefox 128 or later or Fx 115.13.0esr or later (115.21.0esr is current) on the older Firefox 115 ESR channel. https://support.mozilla.org/en-US/kb/root-certificate-expiration Either update in your Linux distro updates package manager. If no more package updates then your version of Linux distro may be EOL with no more updates. Another option is to use the Linux tarball archive from https://www.mozilla.org/firefox/all/ . The basics is to extract the archive and run the firefox script or firefox-bin to start Firefox.