Thanks to a report from Markus Thum, we realized that the repository syncing scripts did not support DEB packages without a Maintainer field at the control file.
This was never a problem because Debian and Ubuntu DEB packages always have this field (it is mandatory according to their policies).
But the new "scap-security-guide-*" DEBs don't have this field at this moment.
We intend to fix this in collaboration with the SLE package maintaners (as we just build the package for Ubuntu/Debian from their sources), but that is going to take some time, and it would require republishing the client tools for Uyuni.
While this problem does not break the repository syncing scripts, it shows an error on-screen, or at the logs (that produces an email each time an automated sync is launched).
For this reason we decided to use the Patch procedure to fix this issue at the server (in the end packages without the Maintaner field are valid ), instead of waiting until Uyuni 2021.06 is released.
You can apply the patch by following the instructions at: https://www.uyuni-project.org/pages/patches.html#server
Of course, the fix will be part of Uyuni 2021.06 as well, so it's not required if you don't manage Debian or Ubuntu clients.