Apparently it’s employees working with their own circadian rhythm. Which actually can be a nightmare to deal with, unless you have really explicit boundaries. Otherwise the nightowl group gets dragged into morning meetings and the 9-5 group ends up having to field questions when they’re winding down for the night.
Management probably loves it because without boundaries everyone ends up working extra hours in a way that’s very stressful but the nature of it makes it difficult for people to even realize they’re working overtime.