I don’t know about IVAO, but I do know that VATSIM purposefully kicks X-Plane players if they cannot maintain 20fps, since the entire simulation slows down, and thus causes problems with aircraft spacing.
If the weather (specifically the winds) are drastically different between FS2020 and the other sims, I can see that causing similar problems for controllers. On top of that, if a controller gives you an altimeter setting, and it’s drastically different than what you have in the sim, there may be some other problems that need to be contended with.
I doubt it’s too much of an issue right now considering FS2020 doesn’t have too many airliners that are fully functional in the IFR environment now, but eventually it is an issue that likely needs to be addressed.