Why is Face ID failing after updating to iOS 18.3.1?

I wanted to give everyone an update... I couldn't get this resolved so I scheduled a Genius appointment.

They confirmed they couldn't get it to work... some speculation that the front-facing sensors for Face ID were about to fail, and that the 18.3.1 update might have just taken them over the edge. I'm not sure if I totally buy that, but they were able to resolve my issue by replacing the physical hardware part. They did the repair in an hour while I waited. Very professional and also very quick repair in my opinion.

The two sensors at play are not the clear front facing camera we use for selfies, but rather the two dark colored lenses to the left of the earpiece/speaker.

Again 12 Pro Max with AppleCare, here's what they replaced:

TrueDepth Camera, iPhone 12 Pro Max

Item Number: 661-23799

Cost without AppleCare $169.00

The "TrueDepth camera" on an iPhone 12 Pro Max refers to the front-facing camera used for facial recognition technology, known as Face ID, which captures detailed depth data of your face to securely unlock your phone; it is a 12MP camera on the iPhone 12 Pro Max. 

I had this repaired 5 days ago and everything is still working great.