Apt repository error message when updating KDE Neon testing


This morning I got an error when I was updating my KDE NEON testing edition via Discover. The update process was not interrupted and I had some packages installed (mesa and Gnome applications). But I’m not sure if its a problem that needs to be fixed.

The error message is this:

W: file:/var/lib/preinstalled-pool/dists/jammy/Release.gpg: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
E: The repository 'http://archive.neon.kde.org/testing jammy Release' no longer has a Release file.
W: Updating from such a repository can't be done securely, and is therefore disabled by default.
W: See apt-secure(8) manpage for repository creation and user configuration details.
E: http://archive.neon.kde.org/testing jammy Release is not (yet) available (Redirection loop encountered

What does it mean and is there a serious issue?

Thanks in advance for helping!