How to update Firefox on Ubuntu Linux

tldr;

# Backup the old version
sudo mv /opt/firefox /opt/firefox_bak

# Untar the new Firefox
sudo tar xjf firefox-*.tar.bz2 -C /opt

# Remove the tar from Downloads
rm -r ~/Downloads/firefox-*.tar.bz2

I installed Firefox on Kubuntu with tarball (no snap nor flatpak):

1. I went to: https://www.mozilla.org/en-US/firefox/new/ , and downloaded the tarball
2. sudo tar xjf ~/Downloads/firefox-*.tar.bz2 -C /opt/
3. sudo ln -s /opt/firefox/firefox /usr/bin/firefox
4. rm -r ~/Downloads/firefox-*.tar.bz2

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When it came to updating Firefox (I got a pop-up in top right corner of the application), I downloaded a new version (used to have 100.x, now I downloaded 101.x), and I used the following commands:

# Backup the old version
sudo mv /opt/firefox /opt/firefox_bak

# Untar the new Firefox
sudo tar xjf firefox-*.tar.bz2 -C /opt

# Remove the tar from Downloads
rm -r /Downloads/firefox-*.tar.bz2

Graphic from: https://en.wikipedia.org/wiki/Red_fox