Exactly, the GSX manual suggest some default keybinds that should be disabled, but that assumes you are using a default settings, if you added other keys that are used by GSX, you must disable them in the sim as well.
That's a simulator limitation that started with MSFS 2020. In FSX or P3D, developers could *temporarily* "steal" a key from the sim entirely, do what they need to do with it, and give it back. The only possible issue of this approach, is that two application might try to do this at the same time, so only one of them would work, but it was easy enough to solve if at least one of the conflicting 3rd party apps had the ability to redefine its keys.
This feature has been removed from Simconnect so, whenever a key is used, it's always passed back to the simulator so, instead of "risking" a faulty addon to steal a key permanently from the sim because it had a bug and it never gave it back, we are now *always* get a conflict no matter what, because both functions are executed at the same time, so the limitation that was supposed to be placed to prevent those rare bugged addons, resulted in a conflict every time the sim and the 3rd party app want to use the same key.
