I have the same problem. I used FROM ubuntu:21.10
but build result
Ign:1 http://archive.ubuntu.com/ubuntu impish InRelease
Ign:2 http://security.ubuntu.com/ubuntu impish-security InRelease
Ign:3 http://archive.ubuntu.com/ubuntu impish-updates InRelease
Err:4 http://security.ubuntu.com/ubuntu impish-security Release
404 Not Found [IP: ***]
Ign:5 http://archive.ubuntu.com/ubuntu impish-backports InRelease
Err:6 http://archive.ubuntu.com/ubuntu impish Release
404 Not Found [IP: ***]
Err:7 http://archive.ubuntu.com/ubuntu impish-updates Release
404 Not Found [IP: ***]
Err:8 http://archive.ubuntu.com/ubuntu impish-backports Release
404 Not Found [IP: ***]
Reading package lists...
E: The repository 'http://security.ubuntu.com/ubuntu impish-security Release' does not have a Release file.
E: The repository 'http://archive.ubuntu.com/ubuntu impish Release' does not have a Release file.
E: The repository 'http://archive.ubuntu.com/ubuntu impish-updates Release' does not have a Release file.
E: The repository 'http://archive.ubuntu.com/ubuntu impish-backports Release' does not have a Release file.
"Ubuntu 21.10 (Impish Indri) End of Life reached on July 14 2022".
Then I changed 21.10 to 22.04 and run build (after apt-get update)
Reading package lists...
E: Problem executing scripts APT::Update::Post-Invoke 'rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true'
E: Sub-process returned an error code
Edit: Then I changed previous LTS version (FROM ubuntu:20.04) and everything works