Apple says that the clearance between the display and the keyboard is designed to very tight tolerances, which can be problematic. Covering the camera can also cause issues with automatic brightness and True Tone.
If you close your Mac notebook with a camera cover installed, you might damage your display because the clearance between the display and keyboard is designed to very tight tolerances. Covering the built-in camera might also interfere with the ambient light sensor and prevent features like automatic brightness and True Tone from working. As an alternative to a camera cover, use the camera indicator light to determine if your camera is active, and decide which apps can use your camera in System Preferences.
The warnings from Apple likely stem from complaints from MacBook Pro owners who have seen their displays crack after covering the camera, and there are multiple reports and warnings on sites that include MacRumors and Reddit. The issue appears to be especially bad with the new 16-inch MacBook Pro models that have thinner bezels.
MacRumors forum member Dashwin, for example, put a webcam cover on his 16-inch MacBook Pro in April and the result was a crack in the display under where the camera is located.
The latest MBP 16 inch with the thin tiny bezels and display comes at a cost of breakage with the tiniest of forces with a webcam cover in place. The internal display no longer works and I’ve had to connect it to an external display. I’ve had one of the exact same webcam covers on my 2011 MBP with no issues whatsoever for many years.
Damage from applying a webcam cover to the camera is considered accidental and can be repaired under AppleCare+, but it’s quite possible it’s an issue that Apple won’t fix for customers that don’t have AppleCare+, and it’s an expensive fix.
Apple says that customers concerned about illicit camera access should watch for the green light that comes on when the camera is activated. The camera is engineered so that it can’t be accessed without the indicator light turning on.
MacBook owners can also control which apps have access to the built-in camera as users must grant permission for camera use on any operating system after macOS Mojave. For those who do need to cover the camera, Apple recommends a camera cover that’s not thicker than the average piece of printer paper (0.1mm) and that does not leave adhesive residue.