ubuntu update automatic to latest version

You appear to be using a Ubuntu supplied build of Firefox 88.0 and if there are no more Firefox package updates then that likely means your version of Ubuntu or a flavour of Ubuntu is EOL in package repository updates. To get Firefox updates from Ubuntu or related Ubuntu distro you need to use a currently supported version of the distro to get package updates as to why you are stuck on that old Firefox version. You can also use the Linux Firefox tarballs from Mozilla as they get internal updates from Mozilla like the macOS and Windows versions does. Just need to make sure the Firefox folder has read/write permissions for the user to get internal Firefox updates. Note if you have 32-bit Linux then Mozilla has dropped 32-bit Linux support starting Firefox 145.0 and on so you should use the Firefox 140 ESR instead. https://support.mozilla.org/en-US/kb/install-firefox-linux https://www.firefox.com/download/all/