I have absolutely no idea what you're talking about.
Any fullscreen games will automatically minimize when alt-tabbed out of, due to how fullscreen mode works (the OS hands control of the display over to the game and stops rendering itself in the background). This is one reason why a second monitor is considered basic livestreaming hardware, as it will let you keep OBS on it to preview the stream going out while still playing fullscreen games on the main monitor.
OBS is not a fullscreen application, so will not minimize on its own.