Another possibility: your teams are working less now.

Yes true, that is a possibility and something that's quite hard to police remotely. It doesn't feel likely, everyone's working kind of the same, booking the same hours and overtime is no different, but I can't rule it out.

It'd mean that hundreds of people would all be goofing off silently. I'd expect at least overtime bookings to decrease and they haven't - even with our strong incentives to not book o/t.