That should indeed be Firefox 78.10.0 esr. Btw the current Fx 78.0 ESR is actually fx 78.'''14'''.0 esr. https://ftp.mozilla.org/pub/firefox/releases/78.14.0esr/linux-x86_64/en-US/ Fx 78.'''15'''.0 esr out in October will be the last for the old Fx 78.0 ESR branch. Perhaps you have Fx 90.0.2 installed on system also either by tarbal or by package build in your package management. So whatever method you are using to start Firefox is pointing to Fx 90.0.2 instead. The current Release is 92.0 as 90.0.2 is old now. https://www.mozilla.org/firefox/releases/ The tarbal is just an archive and there is no installer or setup so you need to run the firefox script in the Firefox folder to start it whether by CLI or by a created launcher on desktop or panel.