Apple Watch and Apple Health

Lately I have noticed that my Apple watch series 5 didn't track my activity quite right. I fixed it by restoring the condition calibration data. I was just looking into the Apple Health app - settings - devices - and saw both my apple watch and iphone. But when clicking Apple watch it says 'This Apple Watch is no longer connected with this Iphone' an this troubles me. I don't understand why this shows up because my Apple Watch is obviously connected with my Iphone because I receive other notifications. Can somebody explain?