About that front-facing camera: the dot projector has moved from the edge to the center of the module this year, but it also holds a little secret.

The flood illuminator, previously a part of the display—and a necessary component of Face ID—has been integrated into this new dual-purpose module.

With the display assembly now independent from Face ID hardware, you might be thinking display and Face ID swaps are easier than ever now! Right? Well, hold that thought.

Face ID works even when we disconnected the front sensor assembly. However, any display replacement knocks out Face ID.* We tried transferring the sensors along with the old display and the Face ID hardware, but no dice. Something on the display is serial-locked to the Face ID hardware.

TL;DR: Screen replacements outside Apple's authorized repair network lose all Face ID functionality.

*Update, Dec. 2021: In iOS 15.2, Apple waved their magic wand and made this problem go away. Now anyone can replace an iPhone 13 screen without losing Face ID.

Though you'll still get a not-so-friendly Important Display Message, and the new display will show up as an unknown part in the Parts and Service History.