Back when Apple added a fingerprint reader to the iPhone 5s, it made it impossible to replace by anyone other than an authorized technician. That makes some sense – a bogus reader may circumvent security. But over the years more and more components have become difficult to replace.

During its teardown and testing of the iPhone 12, iFixit found that taking the camera out and replacing it with an identical module from another phone causes issues. And not just the error report you get when you swap screens (“Unable to verify that this iPhone has a genuine Apple display”).
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https://www.gsmarena.com/iphone_12_cameras_can_be_replaced_only_by_official_apple_technicians-news-46060.php