🔥🔥🔥RAOF🔥🔥🔥Aww, yeah. That's what I'm talking about.
The speed, not the strange colours. That's gnome-screenshot interacting badly with the nvidia drivers.
Relatedly: you can run Steam Big Picture mode in a window with “steam -tenfoot -windowed”.
You might want to do this if, for example, you've got a 4K display and the regular client is a tiny tiny vision test.