Health App / Sleep - doesn't see Sleep as a source of sleep data (only previous external app)

Hello everyone,

I got recently Apple Watch 8 and I have a problem in setting up the sleep tracking in the Health app. In the past I have used a fitness band from Xiaomi and its app (Zepp Life) was the source of sleep data in the Health app on my Iphone. Now this app and its data has been removed from the Iphone (the device turned off and turned on again), but it keeps on appearing as a (inactive) source of sleep data (please see the screenshot). So frustrating, it's like the Iphone got infected with the Zepp Life app :-(. At the same time, the Sleep app is not visible as a source of data, so that I could prioritize them on the list of data sources ('Sleep schedules' and 'Sleep duration goals' recognized the Sleep app right away and they work fine). As a result my sleep gets not tracked since I got the Apple watch. Does anyone has a solution for that? Many thanks in advance for your support.