marowi
This warning occurs because the MariaDB MaxScale repository started using a new GPG key, and servers that already had the repository configured do not have this key installed.
For now, Enhance does not fix this automatically, because this is an APT / operating system–level issue. The fix needs to be applied on each affected server.
I had exactly the same problem and fixed it by manually installing the new MariaDB keyring. Just run the following commands on the server:
After that, apt update works normally again.
Best regards