In this link, Apple states we can know when a user is in bed vs sleeping and compare their quality of sleep by it. Only, in iOS 18, Apple no longer reports inBed time samples for the Apple Watch. I get why they stopped doing this for the phone, but why the watch? Bug?
My app was using the inBed times for this very purpose and now only works for Garmin and Oura who still report inBed times.
https://developer.apple.com/documentation/healthkit/hkcategoryvaluesleepanalysis