Comment 3 for bug 2045086

This appears to be an artifact of the image creation process. I can also confirm that the /etc/apt/sources.list file in the image has a timestamp at the image creation date, not the cloud-init launch date. And cloud-init only writes /etc/apt/sources.list.d/ubuntu.sources.

root@unique-terrapin:~# lsb_release -sc
No LSB modules are available.
noble
root@unique-terrapin:~# cat /etc/cloud/build.info
build_name: server
serial: 20231213
root@unique-terrapin:~# ls -l --full-time /etc/apt/sources.list
-rw-r--r-- 1 root root 2403 2023-12-13 08:38:45.000000000 +0000 /etc/apt/sources.list
root@unique-terrapin:~# egrep 'Writing.*/etc' /var/log/cloud-init.log
2023-12-14 19:54:04,260 - util.py[DEBUG]: Writing to /etc/hostname - wb: [644] 16 bytes
2023-12-14 19:54:04,363 - util.py[DEBUG]: Writing to /etc/netplan/50-cloud-init.yaml - wb: [600] 389 bytes
2023-12-14 19:54:05,613 - util.py[DEBUG]: Writing to /etc/sudoers.d/90-cloud-init-users - wb: [440] 131 bytes
2023-12-14 19:54:09,640 - util.py[DEBUG]: Writing to /etc/apt/sources.list.d/ubuntu.sources - wb: [644] 3097 bytes