https://youtu.be/5Z07Vn4e8gA
There are two metal tabs on either side facing the rear of the car. You can see them on the video link at about the 33 second mark. Those guys can bend and make it very difficult to remove the light fixture. You will have to work with it possibly with two screwdrivers to maneuver the metal clips to allow the fixture to be removed. Just be gentle and patient and you’ll get it out.