There's an issue with your iPhone's ability to use Face ID

You seem to be in Beta. (Based on your Profile)

This is not the right forum to discuss beta

When you experience an issue or something that does not work as expected in beta, send your feedback directly to Apple with Feedback Assistant.

You can’t get help for a beta version in this public forum. Most likely it’s a hardware problem, so try the Get Support link at the top of this page, as it is probably unrelated to the beta.