There are no metrics between from 2nd Feb 06:30 CET and an hour forward (05:30-06:30-ish UTC), FRA datacenter. I see the same thing on both the db-app and my other app in this region and there isn’t anything in the logs.
Majority of the traffic to those apps is the healthchecks you are doing… so the flatline might be them just not running 
Attaching some screenshots of the graphs.
