FaceID is weird too -- as a test scenario, I've noticed that in situations where it can't authenticate my face even after multiple attempts, if I then enter my passcode, lock the phone, and then try FaceID again (without moving the phone or my face or anything else) it will unlock immediately. Almost as if it's thinking "the passcode was verified within the last N minutes, so the next time FaceID tries to authenticate, use fewer face matching points" or something... whatever it is, it's definitely happening because I've tried it on at least my past 2 iPhones (11 Pro and 13 Pro) and it works every time.