When I try to use Animoji, I see "Tap to resume"
Today, I went back to the Apple Store.

After running some tests, they were able to determine a problem with the telephoto lens and Face ID. (Curiously, they saw someone with the same problem earlier that day.)

Because my phone was still within its warranty period, they replaced it free of charge.

Your mileage may vary, but it's worth a shot!