snap remove --purge thunderbird && apt remove thunderbird
snap remove --purge firefox && apt remove firefox
add-apt-repository --ppa ppa:mozillateam/ppa
Prefer any Mozilla package and prevent installing any Thunderbird & Firefox package as a snap from the PPA.
echo '
Package: *
Pin: release o=LP-PPA-mozillateam
Pin-Priority: 1001
Package: firefox*
Pin: release o=Ubuntu
Pin-Priority: -1
Package: thunderbird*
Pin: release o=LP-PPA-mozillateam
Pin-Priority: 1001
Package: thunderbird*
Pin: release o=Ubuntu
Pin-Priority: -1
' > /etc/apt/preferences.d/mozilla
echo 'Unattended-Upgrade::Allowed-Origins:: "LP-PPA-mozillateam:${distro_codename}";' > /etc/apt/apt.conf.d/51unattended-upgrades-firefox
Update the ap database to be sure.
apt update
Where are packages installed from?
apt policy thunderbird
apt policy firefox
apt install firefox
apt install thunderbird