Uneven brake wear on rear brake pads
Likely something is sticking.
Yep, caliper or flex hose.
It is possible that one of your guide pins is sticking and needs to be greased.
just so you know there is a recall on your front brake hoses.
Lincoln Recall 20S42: Front Brake Hoses Could Rupture — 2017 MKX | CarComplaints.com
Make sure rear calipers are firmly attached. Is this problem occurring on both right and left side? If so then maybe that’s normal for this car’s rear brake system configuration esp if the uneven wear means more on the inside pad than the outside pad or visa versa.