iphone Xs max after updating ios 13.3 my face id is not working

Did you this?

Reset Face ID

If you still need help, reset Face ID, then set it up again. Go to Settings > Face ID & Passcode and tap Reset Face ID. Then tap Set up Face ID to set it up again.

If you can’t enroll your face, take your device to an Apple Retail Store or Apple Authorized Service Provider or contact Apple Support.

So what happens when you follow the instruction given to you on the phone?

If Face ID isn't working on your iPhone or iPad Pro - Apple Support

Happened to my iPhone XS also, the face ID intermittent working and battery drain fast even on idle mode..

Follow the steps provided in the link I gave.

I have no issue with face id ios 13.3 on my XS max.

In my first response to you, go back and click on it.