You are new .. so I think it might be worthwhile to point at the wiki:
And maybe specifically mhwd/gfx cards:
But to get down to your scenario ..
You have a dual-gfx system with intel+nvidia.
PRIME is handling this.
The intel will run by default, and the nvidia will be used if you call it.
glxinfo | grep 'renderer string'
prime-run glxinfo | grep 'renderer string'
When you run those commands you should get intel the first time, and nvidia the second because you used
If that all works your system is acting normal.
You can search the interwebs for more info, including the arch wiki:
But most likely the main thing people want to know is about
Dont launch steam with prime-run.
Rather edit game launch options to be exactly:
And that game will run on the nvidia card.