The insurance company didn't inform me of the loss, and then the 4S shop contacted me after the car was repaired. Is this reasonable?

Well, when the accident is serious, the insurance company can't determine the damage immediately. You need to go to your designated repair shop to disassemble it before you can determine the damage. At the same time, the insurance company and the repair shop will negotiate this matter. After your car is repaired, the insurance company can repair the damaged place. If you are not in a hurry to use the car, you can pay directly to the repair shop to pick it up. If you need it urgently, you have to pay a deposit equivalent to the repair fee to pick up the car. When you pick up the car, let the repair shop give you a receipt, and then it is reasonable to refund more and make up less after the claim is settled. When you pick up the car, you need to make an agreement with the repair shop about the warranty and check your car condition carefully. Don't take it away until you confirm it. You can even ask the repair shop to issue your damaged parts. Of course, if you are an expert, you can see if they have tampered with you. If you don't know how to do it, forget it.

Further reading: How to buy insurance, which is good, and teach you how to avoid these "pits" of insurance.