my daughter has a 1996 cadillac sedan deville that bottoms out on bumps sit to low scrubs in and out of parking lots, I look underneath and did not see shocks or struts, did see what might be a air dcompressor mounted on passenger side in rear could this be a compressor motor mount in rear or could air bags be applicable and malfuntioning?
Sounds like there is a hydraulic system installed and if so than that’s what the issue is. Find out the make of the system and research how to readjust the traveling parameters so that the car is not as low. This will solve many issue including scraping everything. The hydraulic system needs to be readjusted, that’s it.