It looks like the feature was removed to swipe up from the bottom to enable a rescan of Face ID if the first time did not catch. This is no longer working on beta 2.
Update: Second scan of Face ID disabled only when Apple Maps is running in the background. With Apple Maps not navigating, swipe up for second rescan now works.
Update: Second scan of Face ID disabled only when Apple Maps is running in the background. With Apple Maps not navigating, swipe up for second rescan now works.