Apple Watch Series 7: No cardio fitness (VO2max) anymore

Since the update to iOS 17.2.1, it feels like the cardio fitness (VO2max) in health app on my iPhone 14 Pro is no longer updated, even though I have done 2.5 hours of walking training today. Silence since 21.12.2023...

To prevent questions in this regard: I train practically every day and so far the cardio fitness has been correctly updated every day.

Apple Watch 7, WatchOS: 10.2

iPhone 14 Pro, iOS: 17.2.1