If turn on the headlights and start the engine, and then open the door, the material on the headlights selection will be dropped, and it will be dropped on any selections nearby.
At the same time, the created light sources do not disappear - which means that the scripts have nothing to do with it.
If I turn off the engine light material may return
Everything related to changing the material on the headlights / selections on the roof does not go through scripts with an arbitrary reset - this is done by the game engine - this can be seen in the logs

Before one of previous updates, everything worked correctly.

This bug applies to any car, include native game cars

This also shows up on a vanilla too...