One  of the disturbing elements that has come out of Covid is the number of masked creepy people prowling the streets in the early hours of the morning. In normal times the police would be entitled to stop someone wandering around in a mask in the middle of the night. Now, not so much. There is no good reason for cycling around in the very early hours of the day wearing a mask. I doubt if these people are the sort who really care about the danger of giving folk Covid. And at 4am there are not generally a lot of people around to give Covid to. But the mask might make it hard for a victim of crime to identify their attacker.