When you look at websites on this subject, it seems the metal towball may or may not cause reversing sensor operation depending on make of car, as you are looking for a decent sized dead spot between the sensors each side of the middle of the rear bumper so the towball does not interfere. Could find nothing specifically on the Ecosport unfortunately. Maybe another owner with a towball may answer this.
Also some cars fit a switch for switching off the reversing sensor circuit, if you are towing a trailer or caravan, and you reverse it, so you do not get sensor sound.
Here is a youtube video showing how to detect the dead spot distance out from the bumper to see if a towball causes detection or not, and they do recommend a removable towball that plugs into the towbar. Any towbar/towball company would have to do this test before fitting, prove it does not interfere, before you part with your money.