Yes, the problem is indeed the graphics. To be more precise, in the nouveau driver. It often worked badly for me and caused bad experiences in other distributions.
The actual solution:
- Load to console mode
- Install proprietary driver with this command
$ sudo dnf install --enablerepo rolling-x86_64-non-free nvidia-dmks-kmod nvidia-settings
After reboot and now I have no problems with any desktop environment or display manager. Except for the blackened Welcome. I read that the proprietary driver is not officially supported by your distribution. So will there be any problems with it afterwards?