From Ubuntu 20.04 LTS onwards, the Ubuntu Server Live Installer is the preferred installation media for Ubuntu Server installs, and the legacy installer based on debian-installer is deprecated. To ease this transition, media was published for the legacy installer as part of the 20.04 and 20.04.1 releases, but we are not providing legacy images for further point releases. There is no guarantee that these outdated legacy images will continue to work.
We are constantly working on improving our products for you. The latest version of the Ubuntu Server Live Installer provides auto-install and auto-update capabilities, an interactive SSH session, a more resilient bootloader and much more. We encourage you to give it a try and let us know about any features you find missing - either on our Ubuntu discourse or by reporting a bug on Launchpad.
Thank you.