I noticed this as well. When i select the car and while shown while loading an event, the car looks fine. When the loading ends my car looks trashed again, scratches allover the car, same goes for the AI cars. 😩
I hope this gets fixed soon, it's annoying. 😅
EDIT: Selecting another livery will make the car "clean" again. Until you used it in a race, then the car will always show banged up again while using that livery. Changing it back and forth doesn't help.
The trashed looks seems to carry over to other modes as well...
So once a livery is used, it will always look trashed at the start of a race, until they fix this bug.