I did a new installation of Fedora 30 KDE spin on my machine (BIOS system, NVidia card Geforce GT 130M). After the first login into the KDE desktop, the Desktop crashes or the system freezes.
The reason for the issues causing that Fedora 30 KDE crashes:
There is an incompatibility between qt 5.xxx and the nouveau driver for certain NVidia legacy cards (in my case it is the NVidia GeForce GT 100M series) and so the deskop freezes or crashes. An installed Debian buster KDE has the same issues, but there are only some programs which are crashing (older kernel and an older plasma version) and not the whole desktop.
Workaround for that issues: start the your system, wait until the Desktop crashes and connect to your network and press “CTRL” + “ESC” to start the System-monitor. Start a console and your browser via the System-monitor. Go to http://rpmfusion.org and follow the instruction for your NVidia graphic card and reboot.
Where I can report this bug, so that RPM Fusion (NVidia drivers!) will be included on demand in future releases of Fedora KDE spin during the installation?