https://wccftech.com/iphone-12-logic-board-swapping-face-id-camera-display-battery-errors/

It was found out previously during a comprehensive teardown by iFixit that replacing the camera modules of the iPhone 12 and iPhone 12 Pro won’t be possible unless you have access to Apple’s proprietary diagnostic tool. However, the problem for independent repair parties is that the cameras behaving erratically is only just the beginning.

One YouTuber discovers this by disassembling two iPhone 12 models and swapping out their logic boards. Keep in mind that despite being original parts, he’s met with a variety of errors, which concludes that Apple doesn’t want anyone repairing its devices other than the company or its authorized repair partners.