Are you installing using a Kylin package manager/repository, or from Mozilla? See: Install Firefox on Linux.

通过存储库安装，.deb方式安装。现在缺少两个安装包，分别为firefox_91.0+build2-0ubuntu0.18.04.1.deb firefox-geckodriver_91.0+build2-0ubuntu0.18.04.1.deb。需要X86架构

You can try Firefox from the official Mozilla server if you currently use a version from the repositories of your Linux distribution to see if it behaves differently.

• https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

Verify that you meet the System Requirements (GTK+ and GLib) for the current Firefox release.

• https://www.mozilla.org/firefox/system-requirements/
• https://www.mozilla.org/firefox/133.0.3/system-requirements/

Support for the old Ubuntu 18.04 LTS released back on April 26, 2018 ended on May 31, 2023. https://ubuntu.com/blog/18-04-end-of-standard-support

So you would would not get anymore package updates since unless you pay for a Ubuntu Pro subscription to get support up to in 2028. Perhaps the most current you may get if you kept Firefox updated in packages may have been the old Firefox 102.11.0 released on May 9, 2023.

The tarbal version from Mozilla will still get internal Firefox updates from Mozilla as Linux system requirements have not changed much in a long time. Just make sure the Firefox folder has read/write permissions for the user as a easy way is to have Firefox folder in Home.