I have updated gnome-shell-extension-ubuntu-dock from focal-proposed and it doesn't fix the issue for me at the moment. I can guess that this is because yaru-theme is not yet updated in focal-proposed.
gnome-shell-extension-ubuntu-dock (68ubuntu1~20.04.1)
yaru-theme-gnome-shell (20.04.6)
I have updated gnome-shell- extension- ubuntu- dock from focal-proposed and it doesn't fix the issue for me at the moment. I can guess that this is because yaru-theme is not yet updated in focal-proposed. extension- ubuntu- dock (68ubuntu1~20.04.1) gnome-shell (20.04.6)
gnome-shell-
yaru-theme-