Primer usually refers to the bottom electrophoretic layer and intermediate coating of car paint. If the scratch hurts these two layers, it means that the scratch depth is deep.
The color of the primer is different from that of the body paint. If you can see different colors in the scratches, you must have hurt the primer.
Some car owners may take measures such as car washing, waxing and polishing to repair scratches. These methods are also effective. But if the scratch can't be repaired, it is that the primer has been scratched.