USS is usually referring to the Ultrasonic Parking Sensors that got deleted when Tesla wanted to save costs in late 2022. These parking sensors are visible as little circles on the bumpers just like many other luxury cars have them. All modern Tesla models used to have USS Parking sensors and used them for parking assistance to the driver.
The FWDs also have “ultrasonic sensors” but those are used for the doors to detect nearby objects and not damage themselves. These are only on the Model X. As far as we know, these FWD Sensors are still present.
Auto present doors on the Model X relied on both the front left fender Parking Sensor and the left FWD Sensor to triangulate a person approaching with their key and detect nearby objects for the front driver door. With the now absence of the left fender Parking USS, the auto-presenting doors don’t have enough data to know how close or far objects are and thus only auto-present a tiny bit (which is the behavior when it used to detect close by objects and tries to avoid opening the front door all the way).