Comment 10 for bug 2034664

gnome-shell-extension-ubuntu-dock is installed in Ubuntu Full install in the repository mantic/main so you (relese team) should explain...

https://cdimages.ubuntu.com/daily-live/pending/mantic-desktop-amd64.manifest

corrado@corrado-n4-mm-1005:~/Videos$ apt policy gnome-shell-extension-ubuntu-dock
gnome-shell-extension-ubuntu-dock:
  Installed: 87ubuntu1
  Candidate: 87ubuntu1
  Version table:
 *** 87ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu mantic/main amd64 Packages
        500 http://archive.ubuntu.com/ubuntu mantic/main i386 Packages
        100 /var/lib/dpkg/status
corrado@corrado-n4-mm-1005:~/Videos$ apt show gnome-shell-extension-ubuntu-dock
Package: gnome-shell-extension-ubuntu-dock
Version: 87ubuntu1
Priority: optional
Section: gnome
Origin: Ubuntu
Maintainer: Marco Trevisan <email address hidden>
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Installed-Size: 913 kB
Depends: gnome-shell (<< 46~), gnome-shell (>= 45~), dconf-gsettings-backend | gsettings-backend
Replaces: gnome-shell-extension-dashtodock
Homepage: https://github.com/micheleg/dash-to-dock/blob/ubuntu-dock/README.md
Task: ubuntu-desktop-minimal, ubuntu-desktop, edubuntu-desktop-gnome
Download-Size: 117 kB
APT-Manual-Installed: no
APT-Sources: http://archive.ubuntu.com/ubuntu mantic/main amd64 Packages
Description: Ubuntu Dock for GNOME Shell
 A dock for the Gnome Shell, default Ubuntu experience.
 .
 This extension is a modified version of Dash To Dock with different defaults.
 Dash To Dock can be installed to replace it and give more (but unsupported)
 configuration options.

corrado@corrado-n4-mm-1005:~/Videos$