In the iOS 13.5 beta, released this morning, Apple has streamlined the speed with which the passcode pops up when a person wearing a mask is detected, making it easier to get into an iPhone with a passcode when Face ID fails.
Speedier access to the passcode interface is noticeable when you swipe upwards on the Home screen when unlocking the iPhone, as this action now immediately brings up the passcode interface if your face is covered by a mask.
Previously, the iPhone would attempt to initiate Face ID first, creating a few seconds of delay before the passcode interface was shown. The new, speedier passcode entry method makes it quicker to get into an iPhone.
The feature is available in the current iOS 13.5 beta, which should see a public release in the next few weeks.