The GAIA-2's screen saver is always on to prevent the OLED (Organic Light Emitting Diode) display from burn-in and cannot be turned off.
You can change the type of screen saver and the time (in minutes) before it starts to appear.
Go to [MENU] > System > General, set the Screen Saver Type (1-10) and Screen Saver Time (1, 5, or 10 [min]).