When the sim finishes loading at your selected airport and GSX opens on its own, it's from you leaving the last session with the GSX toolbar still enabled in the toolbar.
But this is a known automatic feature of the sim, it remembers which panels were active when exiting/resuming a flight, and will only result in the GSX menu to open, but it won't start any service, until a 0-9 key press is also being sent after the menu opened.
I had the same thing until I noticed that the GSX button was highlighted. Select the GSX button again and it will turn to the same shade as the rest of them and then close your sim
That's in fact what the manual suggests to do when the function of the menu is explained at Page 68:
This is now your normal workflow should be:
• Open the GSX menu from the Toolbar icon when first starting Ground services.
• Don’t close it from the Toolbar while Ground services are performed, always use the Hot-key or the X icon to close the menu.
• Close the menu using the Toolbar icon when you are done with Ground services, usually before take-off.
In brief, the Toolbar Icon should always be left Active while Ground services are required.
But that's more a generic advice to squeeze the tiniest possible bit of performance when GSX is not required, since the menu itself is a running Javascript code that gets interpreted while the Toolbar icon is Active, so there's a tiny bit of impact on the CPU, which becomes null when the Toolbar Icon is Inactive, since the Javascript code is no longer running in that case. It shouldn't cause services starting automatically in any case.
