My face id doesn't recognize my face

My iphone xr already updated to ios 14.2 for a couple days, but suddenly the trouble is appearing now while everything was okay before. Suddenly, my face id doesn't recognize my face and keep asking to passcode. I was tried to follow the instructions on this web bit my iphone keep saying "face id not available now. Try later when the iphone cools down".

I don't understand what that meaning. And I've restarted my face id 🥲. This is so important for me because all important app on my iphone used face id to log in. And now, nothing I can do to it 😔 please help me 🙏🏻