At the moment, screen repairs of the iPhone 13 through third-party service centers make the FaceID system completely useless. The problem apparently is being caused by a new chip present on the flex cable that connects the display to the motherboard. The technicians were reportedly not using the same flex cable after repair.

The process of removing the new chip from the flex cable on the broken screen takes a lot of effort and time, compared to the previous generation iPhones’ screen repair. The new chip reportedly is used to link the display of the iPhone 13 to the unique motherboard inside the device.
Special tools required for screen repairs
The screen repair process of the iPhone 13 also requires special tools which are reportedly not easily available. According to GSMArena, most shops that deal with iPhone repairs do not have the necessary tools for the iPhone 13 screen replacement. As a result, the new iPhone 13s being repaired at third-party repair centers are turning out to be completely useless.
Apple has reported that it plans to push a software update to fix the issue. The update will reportedly allow iPhone 13 devices to run perfectly normal after a screen replacement procedure. It will not require repaired devices to have the same microcontroller chip from the old broken screen.
The upcoming software update for the iPhone 13 will hugely benefit third-party repair shops and also consumers who could get the iPhone 13s repaired for cheaper. Apple has not specified as to when it plans to release the software update but it does not seem far off from public release.
Apple released the iPhone 13 at its September event this year, as part of its flagship smartphone series launch. The company launched the iPhone 13 mini, the iPhone 13, the iPhone 13 Pro, and the iPhone 13 Pro Max.