The transition of Firefox from Deb to Snap was announced in September 2021. Sudo apt remove firefox & sudo snap install firefox Remove the apt version and reinstall snap.Sudo rm -rf /etc/apt/preferences.d/mozilla-firefox Sudo add-apt-repository -r ppa:mozillateam/ppa echo 'Unattended-Upgrade::Allowed-Origins:: 'LP-PPA-mozillateam:$' ' | sudo tee /etc/apt//51unattended-upgrades-firefox Alternatively, you can turn off unattended upgrades. To ensure that unattended upgrades do not reinstall the snap version of Firefox, enter the following command. Next, remove the snap version of firefox sudo snap remove firefox ' | sudo tee /etc/apt/preferences.d/mozilla-firefox Then, copy and paste the following code in a terminal in one go (don't copy-paste line by line) to prioritize the apt version of firefox over the snap version. sudo add-apt-repository ppa:mozillateam/ppa

You can use the Firefox PPA maintained by Mozilla team. This answer is for the latest stable version of Firefox.

The other answer by Organic Marble is for Firefox-ESR, and the answer by eddygeek is for the beta version.

Mozilla firefox app downlode