swipe

The Notification Center access swipe needs to start from the top or above the top of the display and downward onto the display, and not starting the swipe from on the display and downward.

Use gestures to navigate your iPhone with Face ID - Apple Support

If the Notification Center gesture swipe is starting from the documented spot and is not working, make sure you’re running iOS 14.7.1 and update if not.

Clean your display, and see if that gets things working.

Then try a restart and see if that allows the gesture.

Failing that, remove any case and any protective film that might be in use here, and try again.

Failing all that, then contact Apple as your display might be failing.

How to ➡️ Restart your iPhone - Apple Support