Display replacement has so far been a standard process and the possible use of the services of unauthorized services differed mainly in the quality of the product obtained after the replacement. The functionality of smartphones, however, did not change and after replacing the screen at any service point, all the functions of the phones worked. The situation is different in the case of the latest iPhones from the 13 series, where in order to use all the functions of the phone after replacing the display, it will be necessary to use authorized services.
You will still be able to use your phone if you use unauthorized display swap points. The problem is that then the FaceID function will stop working in the phone, which allows you to unlock the phone with your face. This is due to the fact that Apple has placed a special chip in the cable used to connect the screen to the phone's motherboard. Only points authorized by Apple will have access to the program that allows for its decoding or encoding. Other companies will be able to replace the display by soldering a new screen in place of the old one, but then the FaceID function will not work in the phone, because the chip will detect the change of the display connected by the cable.