I suspect this is because snapd will do 'sudo udevadm control --reload-rules && sudo udevadm trigger' on interface connections. These operations are supposed to be safe but I've seen with my Intel graphics that gnome-shell/X11 will blink when this happens (due to the 'udevadm trigger') but it doesn't crash. I suspect that your particular combination of gnome-shell/X11/nvidia isn't responding particularly well when this happens.
I suspect this is because snapd will do 'sudo udevadm control --reload-rules && sudo udevadm trigger' on interface connections. These operations are supposed to be safe but I've seen with my Intel graphics that gnome-shell/X11 will blink when this happens (due to the 'udevadm trigger') but it doesn't crash. I suspect that your particular combination of gnome-shell/ X11/nvidia isn't responding particularly well when this happens.