Comment 1 for bug 1838199

When you installed Firefox ESR from the stable channel in Ubuntu Software you were installing the application packaged as a snap. The Software Updater and apt or apt-get commands cannot be used to manage snaps which is why you have not been offered an update.

However, when snaps are installed from the stable channel they are automatically updated. An update check runs periodically n the background. If you run the command

snap info firefox

in a terminal you will see a list of available snaps and the date they were released. The last line shows the version that is installed. You can force an update with the command

sudo snap refresh firefox

If no updates are available then an appropriate message is displayed.

The latest version of Firefox ESR available is 60.8.0esr-1 which was released on 8th July.

Please confirm that this is the version that is currently running on each of your machines.