Rocky 8.6 install issue after reboot black screen

Better would be to use rpmfusion or elrepo repositories for installing Nvidia Drivers: NVidia drivers: RPMFusion vs. ELRepo - #2 by stack

In that thread there is a post about using nvidia-detect which will tell you which Nvidia driver is required for your device. Changes are you have the wrong one installed, and is why you have black screen.