Why is my shooting turbo making me prone and making me move automatically in rainbow six siege

Please make sure you haven't mapped more keys in the special/turbo/macros and the double check you're mapping to ensure that your prone key is not the same as your firing key.

If you checked the sections mentioned above and it still does it, please try loading a different profile to see if it's only applicable to that profile or all. It can even be the default console profile.