Unfortunate. However, it seems that is snapd's fault. Here's the important part from the article:

Ubuntu automatically deletes old files from the /tmp directory after a certain number of days. During this cleanup, an important directory used by snap-confine may get removed.

Ubuntu configured systemd-tmpfiles to clean out /tmp after some days. That's why the issue is only present in Ubuntu systems. Therefore, systemd was doing it's job, and it just so happened to create the perfect conditions for a vulnerability in Ubuntu.