Basically this bug: error after updating the beta version https://issues.openmandriva.org/show_bug.cgi?id=2468
If user installs our ISO from SourceForge and updates then dnf will be broken.
There isn't a working ISO on ABF. So perhaps we should not be encouraging anyone to install Lx 4 until we get things back in some working order. Meaning until after we get gpg key issue fixed, mass rebuild done and produce a new ISO and test it internally to be sure it is OK.