Ubuntuのポイントリリース (3つ目のバージョンが上がる)はインストールイメージが作られると上がるっぽいよ。
https://gihyo.jp/admin/clip/01/ubuntu-topics/202208/05
手元のデスクトップは
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 22.04.2 LTS
Release: 22.04
Codename: jammy
で、
$ sudo sh -c 'apt update; apt dist-upgrade -y; snap refresh'
:
The following packages have been kept back:
fonts-ricty-diminished
The following packages will be upgraded:
base-files containerd distro-info docker.io language-pack-en
language-pack-en-base language-pack-gnome-en language-pack-gnome-en-base
libegl-mesa0 libegl-mesa0:i386 libgbm1 libgbm1:i386 libgl1-amber-dri
libgl1-mesa-dri libgl1-mesa-dri:i386 libglapi-mesa libglapi-mesa:i386
libglx-mesa0 libglx-mesa0:i386 libgpgme11 libgpgmepp6 libunwind8
libxatracker2 linux-firmware mesa-va-drivers mesa-va-drivers:i386
mesa-vdpau-drivers mesa-vulkan-drivers mesa-vulkan-drivers:i386
python-apt-common python3-apt python3-distro-info python3-distupgrade runc
thermald ubuntu-release-upgrader-core ubuntu-release-upgrader-gtk ufw
38 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
:
で
Description: Ubuntu 22.04.3 LTS
になったよ(どのパッケージが効いたんじゃろ。
$ dpkg -S /etc/lsb-release
base-files: /etc/lsb-release