What is the TrueDepth camera issue

this is a user to user forum. we cannot tell you what the issue is..

but here is what Apple says about it in the related article you were viewing

What the message means

Using diagnostics in iOS, Apple has detected an issue with your TrueDepth camera that might cause it to not function as expected. This won't prevent you from using your iPhone or iPad, but until your iPhone or iPad is updated or serviced, you might not be able to use Face ID, Animoji, Memoji, and some other features that use the front camera.