Ign:1 https://ppa.launchpadcontent.net/flatpak/stable/ubuntu lunar InRelease
Hit:2 http://dk.archive.ubuntu.com/ubuntu lunar InRelease
Hit:3 http://dk.archive.ubuntu.com/ubuntu lunar-updates InRelease
Hit:4 http://dk.archive.ubuntu.com/ubuntu lunar-backports InRelease
Hit:5 http://dk.archive.ubuntu.com/ubuntu lunar-security InRelease
Hit:6 https://ppa.launchpadcontent.net/graphics-drivers/ppa/ubuntu lunar InRelease
Hit:7 https://ppa.launchpadcontent.net/obsproject/obs-studio/ubuntu lunar InRelease
Err:8 https://ppa.launchpadcontent.net/flatpak/stable/ubuntu lunar Release
  404  Not Found [IP: 2620:2d:4000:1::3e 443]
Reading package lists... Done
E: The repository 'https://ppa.launchpadcontent.net/flatpak/stable/ubuntu lunar Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.